|
@@ -1,1646 +0,0 @@
|
|
|
-# Async.js
|
|
|
-
|
|
|
-[](https://travis-ci.org/caolan/async)
|
|
|
-
|
|
|
-
|
|
|
-Async is a utility module which provides straight-forward, powerful functions
|
|
|
-for working with asynchronous JavaScript. Although originally designed for
|
|
|
-use with [Node.js](http://nodejs.org), it can also be used directly in the
|
|
|
-browser. Also supports [component](https://github.com/component/component).
|
|
|
-
|
|
|
-Async provides around 20 functions that include the usual 'functional'
|
|
|
-suspects (`map`, `reduce`, `filter`, `each`…) as well as some common patterns
|
|
|
-for asynchronous control flow (`parallel`, `series`, `waterfall`…). All these
|
|
|
-functions assume you follow the Node.js convention of providing a single
|
|
|
-callback as the last argument of your `async` function.
|
|
|
-
|
|
|
-
|
|
|
-## Quick Examples
|
|
|
-
|
|
|
-```javascript
|
|
|
-async.map(['file1','file2','file3'], fs.stat, function(err, results){
|
|
|
- // results is now an array of stats for each file
|
|
|
-});
|
|
|
-
|
|
|
-async.filter(['file1','file2','file3'], fs.exists, function(results){
|
|
|
- // results now equals an array of the existing files
|
|
|
-});
|
|
|
-
|
|
|
-async.parallel([
|
|
|
- function(){ ... },
|
|
|
- function(){ ... }
|
|
|
-], callback);
|
|
|
-
|
|
|
-async.series([
|
|
|
- function(){ ... },
|
|
|
- function(){ ... }
|
|
|
-]);
|
|
|
-```
|
|
|
-
|
|
|
-There are many more functions available so take a look at the docs below for a
|
|
|
-full list. This module aims to be comprehensive, so if you feel anything is
|
|
|
-missing please create a GitHub issue for it.
|
|
|
-
|
|
|
-## Common Pitfalls
|
|
|
-
|
|
|
-### Binding a context to an iterator
|
|
|
-
|
|
|
-This section is really about `bind`, not about `async`. If you are wondering how to
|
|
|
-make `async` execute your iterators in a given context, or are confused as to why
|
|
|
-a method of another library isn't working as an iterator, study this example:
|
|
|
-
|
|
|
-```js
|
|
|
-// Here is a simple object with an (unnecessarily roundabout) squaring method
|
|
|
-var AsyncSquaringLibrary = {
|
|
|
- squareExponent: 2,
|
|
|
- square: function(number, callback){
|
|
|
- var result = Math.pow(number, this.squareExponent);
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, result);
|
|
|
- }, 200);
|
|
|
- }
|
|
|
-};
|
|
|
-
|
|
|
-async.map([1, 2, 3], AsyncSquaringLibrary.square, function(err, result){
|
|
|
- // result is [NaN, NaN, NaN]
|
|
|
- // This fails because the `this.squareExponent` expression in the square
|
|
|
- // function is not evaluated in the context of AsyncSquaringLibrary, and is
|
|
|
- // therefore undefined.
|
|
|
-});
|
|
|
-
|
|
|
-async.map([1, 2, 3], AsyncSquaringLibrary.square.bind(AsyncSquaringLibrary), function(err, result){
|
|
|
- // result is [1, 4, 9]
|
|
|
- // With the help of bind we can attach a context to the iterator before
|
|
|
- // passing it to async. Now the square function will be executed in its
|
|
|
- // 'home' AsyncSquaringLibrary context and the value of `this.squareExponent`
|
|
|
- // will be as expected.
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-## Download
|
|
|
-
|
|
|
-The source is available for download from
|
|
|
-[GitHub](http://github.com/caolan/async).
|
|
|
-Alternatively, you can install using Node Package Manager (`npm`):
|
|
|
-
|
|
|
- npm install async
|
|
|
-
|
|
|
-__Development:__ [async.js](https://github.com/caolan/async/raw/master/lib/async.js) - 29.6kb Uncompressed
|
|
|
-
|
|
|
-## In the Browser
|
|
|
-
|
|
|
-So far it's been tested in IE6, IE7, IE8, FF3.6 and Chrome 5.
|
|
|
-
|
|
|
-Usage:
|
|
|
-
|
|
|
-```html
|
|
|
-<script type="text/javascript" src="async.js"></script>
|
|
|
-<script type="text/javascript">
|
|
|
-
|
|
|
- async.map(data, asyncProcess, function(err, results){
|
|
|
- alert(results);
|
|
|
- });
|
|
|
-
|
|
|
-</script>
|
|
|
-```
|
|
|
-
|
|
|
-## Documentation
|
|
|
-
|
|
|
-### Collections
|
|
|
-
|
|
|
-* [`each`](#each)
|
|
|
-* [`eachSeries`](#eachSeries)
|
|
|
-* [`eachLimit`](#eachLimit)
|
|
|
-* [`map`](#map)
|
|
|
-* [`mapSeries`](#mapSeries)
|
|
|
-* [`mapLimit`](#mapLimit)
|
|
|
-* [`filter`](#filter)
|
|
|
-* [`filterSeries`](#filterSeries)
|
|
|
-* [`reject`](#reject)
|
|
|
-* [`rejectSeries`](#rejectSeries)
|
|
|
-* [`reduce`](#reduce)
|
|
|
-* [`reduceRight`](#reduceRight)
|
|
|
-* [`detect`](#detect)
|
|
|
-* [`detectSeries`](#detectSeries)
|
|
|
-* [`sortBy`](#sortBy)
|
|
|
-* [`some`](#some)
|
|
|
-* [`every`](#every)
|
|
|
-* [`concat`](#concat)
|
|
|
-* [`concatSeries`](#concatSeries)
|
|
|
-
|
|
|
-### Control Flow
|
|
|
-
|
|
|
-* [`series`](#seriestasks-callback)
|
|
|
-* [`parallel`](#parallel)
|
|
|
-* [`parallelLimit`](#parallellimittasks-limit-callback)
|
|
|
-* [`whilst`](#whilst)
|
|
|
-* [`doWhilst`](#doWhilst)
|
|
|
-* [`until`](#until)
|
|
|
-* [`doUntil`](#doUntil)
|
|
|
-* [`forever`](#forever)
|
|
|
-* [`waterfall`](#waterfall)
|
|
|
-* [`compose`](#compose)
|
|
|
-* [`seq`](#seq)
|
|
|
-* [`applyEach`](#applyEach)
|
|
|
-* [`applyEachSeries`](#applyEachSeries)
|
|
|
-* [`queue`](#queue)
|
|
|
-* [`priorityQueue`](#priorityQueue)
|
|
|
-* [`cargo`](#cargo)
|
|
|
-* [`auto`](#auto)
|
|
|
-* [`retry`](#retry)
|
|
|
-* [`iterator`](#iterator)
|
|
|
-* [`apply`](#apply)
|
|
|
-* [`nextTick`](#nextTick)
|
|
|
-* [`times`](#times)
|
|
|
-* [`timesSeries`](#timesSeries)
|
|
|
-
|
|
|
-### Utils
|
|
|
-
|
|
|
-* [`memoize`](#memoize)
|
|
|
-* [`unmemoize`](#unmemoize)
|
|
|
-* [`log`](#log)
|
|
|
-* [`dir`](#dir)
|
|
|
-* [`noConflict`](#noConflict)
|
|
|
-
|
|
|
-
|
|
|
-## Collections
|
|
|
-
|
|
|
-<a name="forEach" />
|
|
|
-<a name="each" />
|
|
|
-### each(arr, iterator, callback)
|
|
|
-
|
|
|
-Applies the function `iterator` to each item in `arr`, in parallel.
|
|
|
-The `iterator` is called with an item from the list, and a callback for when it
|
|
|
-has finished. If the `iterator` passes an error to its `callback`, the main
|
|
|
-`callback` (for the `each` function) is immediately called with the error.
|
|
|
-
|
|
|
-Note, that since this function applies `iterator` to each item in parallel,
|
|
|
-there is no guarantee that the iterator functions will complete in order.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A function to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(err)` which must be called once it has
|
|
|
- completed. If no error has occured, the `callback` should be run without
|
|
|
- arguments or with an explicit `null` argument.
|
|
|
-* `callback(err)` - A callback which is called when all `iterator` functions
|
|
|
- have finished, or an error occurs.
|
|
|
-
|
|
|
-__Examples__
|
|
|
-
|
|
|
-
|
|
|
-```js
|
|
|
-// assuming openFiles is an array of file names and saveFile is a function
|
|
|
-// to save the modified contents of that file:
|
|
|
-
|
|
|
-async.each(openFiles, saveFile, function(err){
|
|
|
- // if any of the saves produced an error, err would equal that error
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-```js
|
|
|
-// assuming openFiles is an array of file names
|
|
|
-
|
|
|
-async.each(openFiles, function( file, callback) {
|
|
|
-
|
|
|
- // Perform operation on file here.
|
|
|
- console.log('Processing file ' + file);
|
|
|
-
|
|
|
- if( file.length > 32 ) {
|
|
|
- console.log('This file name is too long');
|
|
|
- callback('File name too long');
|
|
|
- } else {
|
|
|
- // Do work to process file here
|
|
|
- console.log('File processed');
|
|
|
- callback();
|
|
|
- }
|
|
|
-}, function(err){
|
|
|
- // if any of the file processing produced an error, err would equal that error
|
|
|
- if( err ) {
|
|
|
- // One of the iterations produced an error.
|
|
|
- // All processing will now stop.
|
|
|
- console.log('A file failed to process');
|
|
|
- } else {
|
|
|
- console.log('All files have been processed successfully');
|
|
|
- }
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="forEachSeries" />
|
|
|
-<a name="eachSeries" />
|
|
|
-### eachSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-The same as [`each`](#each), only `iterator` is applied to each item in `arr` in
|
|
|
-series. The next `iterator` is only called once the current one has completed.
|
|
|
-This means the `iterator` functions will complete in order.
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="forEachLimit" />
|
|
|
-<a name="eachLimit" />
|
|
|
-### eachLimit(arr, limit, iterator, callback)
|
|
|
-
|
|
|
-The same as [`each`](#each), only no more than `limit` `iterator`s will be simultaneously
|
|
|
-running at any time.
|
|
|
-
|
|
|
-Note that the items in `arr` are not processed in batches, so there is no guarantee that
|
|
|
-the first `limit` `iterator` functions will complete before any others are started.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `limit` - The maximum number of `iterator`s to run at any time.
|
|
|
-* `iterator(item, callback)` - A function to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(err)` which must be called once it has
|
|
|
- completed. If no error has occured, the callback should be run without
|
|
|
- arguments or with an explicit `null` argument.
|
|
|
-* `callback(err)` - A callback which is called when all `iterator` functions
|
|
|
- have finished, or an error occurs.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-// Assume documents is an array of JSON objects and requestApi is a
|
|
|
-// function that interacts with a rate-limited REST api.
|
|
|
-
|
|
|
-async.eachLimit(documents, 20, requestApi, function(err){
|
|
|
- // if any of the saves produced an error, err would equal that error
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="map" />
|
|
|
-### map(arr, iterator, callback)
|
|
|
-
|
|
|
-Produces a new array of values by mapping each value in `arr` through
|
|
|
-the `iterator` function. The `iterator` is called with an item from `arr` and a
|
|
|
-callback for when it has finished processing. Each of these callback takes 2 arguments:
|
|
|
-an `error`, and the transformed item from `arr`. If `iterator` passes an error to this
|
|
|
-callback, the main `callback` (for the `map` function) is immediately called with the error.
|
|
|
-
|
|
|
-Note, that since this function applies the `iterator` to each item in parallel,
|
|
|
-there is no guarantee that the `iterator` functions will complete in order.
|
|
|
-However, the results array will be in the same order as the original `arr`.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A function to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(err, transformed)` which must be called once
|
|
|
- it has completed with an error (which can be `null`) and a transformed item.
|
|
|
-* `callback(err, results)` - A callback which is called when all `iterator`
|
|
|
- functions have finished, or an error occurs. Results is an array of the
|
|
|
- transformed items from the `arr`.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.map(['file1','file2','file3'], fs.stat, function(err, results){
|
|
|
- // results is now an array of stats for each file
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="mapSeries" />
|
|
|
-### mapSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-The same as [`map`](#map), only the `iterator` is applied to each item in `arr` in
|
|
|
-series. The next `iterator` is only called once the current one has completed.
|
|
|
-The results array will be in the same order as the original.
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="mapLimit" />
|
|
|
-### mapLimit(arr, limit, iterator, callback)
|
|
|
-
|
|
|
-The same as [`map`](#map), only no more than `limit` `iterator`s will be simultaneously
|
|
|
-running at any time.
|
|
|
-
|
|
|
-Note that the items are not processed in batches, so there is no guarantee that
|
|
|
-the first `limit` `iterator` functions will complete before any others are started.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `limit` - The maximum number of `iterator`s to run at any time.
|
|
|
-* `iterator(item, callback)` - A function to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(err, transformed)` which must be called once
|
|
|
- it has completed with an error (which can be `null`) and a transformed item.
|
|
|
-* `callback(err, results)` - A callback which is called when all `iterator`
|
|
|
- calls have finished, or an error occurs. The result is an array of the
|
|
|
- transformed items from the original `arr`.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.mapLimit(['file1','file2','file3'], 1, fs.stat, function(err, results){
|
|
|
- // results is now an array of stats for each file
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="select" />
|
|
|
-<a name="filter" />
|
|
|
-### filter(arr, iterator, callback)
|
|
|
-
|
|
|
-__Alias:__ `select`
|
|
|
-
|
|
|
-Returns a new array of all the values in `arr` which pass an async truth test.
|
|
|
-_The callback for each `iterator` call only accepts a single argument of `true` or
|
|
|
-`false`; it does not accept an error argument first!_ This is in-line with the
|
|
|
-way node libraries work with truth tests like `fs.exists`. This operation is
|
|
|
-performed in parallel, but the results array will be in the same order as the
|
|
|
-original.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A truth test to apply to each item in `arr`.
|
|
|
- The `iterator` is passed a `callback(truthValue)`, which must be called with a
|
|
|
- boolean argument once it has completed.
|
|
|
-* `callback(results)` - A callback which is called after all the `iterator`
|
|
|
- functions have finished.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.filter(['file1','file2','file3'], fs.exists, function(results){
|
|
|
- // results now equals an array of the existing files
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="selectSeries" />
|
|
|
-<a name="filterSeries" />
|
|
|
-### filterSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-__Alias:__ `selectSeries`
|
|
|
-
|
|
|
-The same as [`filter`](#filter) only the `iterator` is applied to each item in `arr` in
|
|
|
-series. The next `iterator` is only called once the current one has completed.
|
|
|
-The results array will be in the same order as the original.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="reject" />
|
|
|
-### reject(arr, iterator, callback)
|
|
|
-
|
|
|
-The opposite of [`filter`](#filter). Removes values that pass an `async` truth test.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="rejectSeries" />
|
|
|
-### rejectSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-The same as [`reject`](#reject), only the `iterator` is applied to each item in `arr`
|
|
|
-in series.
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="reduce" />
|
|
|
-### reduce(arr, memo, iterator, callback)
|
|
|
-
|
|
|
-__Aliases:__ `inject`, `foldl`
|
|
|
-
|
|
|
-Reduces `arr` into a single value using an async `iterator` to return
|
|
|
-each successive step. `memo` is the initial state of the reduction.
|
|
|
-This function only operates in series.
|
|
|
-
|
|
|
-For performance reasons, it may make sense to split a call to this function into
|
|
|
-a parallel map, and then use the normal `Array.prototype.reduce` on the results.
|
|
|
-This function is for situations where each step in the reduction needs to be async;
|
|
|
-if you can get the data before reducing it, then it's probably a good idea to do so.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `memo` - The initial state of the reduction.
|
|
|
-* `iterator(memo, item, callback)` - A function applied to each item in the
|
|
|
- array to produce the next step in the reduction. The `iterator` is passed a
|
|
|
- `callback(err, reduction)` which accepts an optional error as its first
|
|
|
- argument, and the state of the reduction as the second. If an error is
|
|
|
- passed to the callback, the reduction is stopped and the main `callback` is
|
|
|
- immediately called with the error.
|
|
|
-* `callback(err, result)` - A callback which is called after all the `iterator`
|
|
|
- functions have finished. Result is the reduced value.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.reduce([1,2,3], 0, function(memo, item, callback){
|
|
|
- // pointless async:
|
|
|
- process.nextTick(function(){
|
|
|
- callback(null, memo + item)
|
|
|
- });
|
|
|
-}, function(err, result){
|
|
|
- // result is now equal to the last value of memo, which is 6
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="reduceRight" />
|
|
|
-### reduceRight(arr, memo, iterator, callback)
|
|
|
-
|
|
|
-__Alias:__ `foldr`
|
|
|
-
|
|
|
-Same as [`reduce`](#reduce), only operates on `arr` in reverse order.
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="detect" />
|
|
|
-### detect(arr, iterator, callback)
|
|
|
-
|
|
|
-Returns the first value in `arr` that passes an async truth test. The
|
|
|
-`iterator` is applied in parallel, meaning the first iterator to return `true` will
|
|
|
-fire the detect `callback` with that result. That means the result might not be
|
|
|
-the first item in the original `arr` (in terms of order) that passes the test.
|
|
|
-
|
|
|
-If order within the original `arr` is important, then look at [`detectSeries`](#detectSeries).
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A truth test to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(truthValue)` which must be called with a
|
|
|
- boolean argument once it has completed.
|
|
|
-* `callback(result)` - A callback which is called as soon as any iterator returns
|
|
|
- `true`, or after all the `iterator` functions have finished. Result will be
|
|
|
- the first item in the array that passes the truth test (iterator) or the
|
|
|
- value `undefined` if none passed.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.detect(['file1','file2','file3'], fs.exists, function(result){
|
|
|
- // result now equals the first file in the list that exists
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="detectSeries" />
|
|
|
-### detectSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-The same as [`detect`](#detect), only the `iterator` is applied to each item in `arr`
|
|
|
-in series. This means the result is always the first in the original `arr` (in
|
|
|
-terms of array order) that passes the truth test.
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="sortBy" />
|
|
|
-### sortBy(arr, iterator, callback)
|
|
|
-
|
|
|
-Sorts a list by the results of running each `arr` value through an async `iterator`.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A function to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(err, sortValue)` which must be called once it
|
|
|
- has completed with an error (which can be `null`) and a value to use as the sort
|
|
|
- criteria.
|
|
|
-* `callback(err, results)` - A callback which is called after all the `iterator`
|
|
|
- functions have finished, or an error occurs. Results is the items from
|
|
|
- the original `arr` sorted by the values returned by the `iterator` calls.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.sortBy(['file1','file2','file3'], function(file, callback){
|
|
|
- fs.stat(file, function(err, stats){
|
|
|
- callback(err, stats.mtime);
|
|
|
- });
|
|
|
-}, function(err, results){
|
|
|
- // results is now the original array of files sorted by
|
|
|
- // modified date
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-__Sort Order__
|
|
|
-
|
|
|
-By modifying the callback parameter the sorting order can be influenced:
|
|
|
-
|
|
|
-```js
|
|
|
-//ascending order
|
|
|
-async.sortBy([1,9,3,5], function(x, callback){
|
|
|
- callback(err, x);
|
|
|
-}, function(err,result){
|
|
|
- //result callback
|
|
|
-} );
|
|
|
-
|
|
|
-//descending order
|
|
|
-async.sortBy([1,9,3,5], function(x, callback){
|
|
|
- callback(err, x*-1); //<- x*-1 instead of x, turns the order around
|
|
|
-}, function(err,result){
|
|
|
- //result callback
|
|
|
-} );
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="some" />
|
|
|
-### some(arr, iterator, callback)
|
|
|
-
|
|
|
-__Alias:__ `any`
|
|
|
-
|
|
|
-Returns `true` if at least one element in the `arr` satisfies an async test.
|
|
|
-_The callback for each iterator call only accepts a single argument of `true` or
|
|
|
-`false`; it does not accept an error argument first!_ This is in-line with the
|
|
|
-way node libraries work with truth tests like `fs.exists`. Once any iterator
|
|
|
-call returns `true`, the main `callback` is immediately called.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A truth test to apply to each item in the array
|
|
|
- in parallel. The iterator is passed a callback(truthValue) which must be
|
|
|
- called with a boolean argument once it has completed.
|
|
|
-* `callback(result)` - A callback which is called as soon as any iterator returns
|
|
|
- `true`, or after all the iterator functions have finished. Result will be
|
|
|
- either `true` or `false` depending on the values of the async tests.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.some(['file1','file2','file3'], fs.exists, function(result){
|
|
|
- // if result is true then at least one of the files exists
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="every" />
|
|
|
-### every(arr, iterator, callback)
|
|
|
-
|
|
|
-__Alias:__ `all`
|
|
|
-
|
|
|
-Returns `true` if every element in `arr` satisfies an async test.
|
|
|
-_The callback for each `iterator` call only accepts a single argument of `true` or
|
|
|
-`false`; it does not accept an error argument first!_ This is in-line with the
|
|
|
-way node libraries work with truth tests like `fs.exists`.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A truth test to apply to each item in the array
|
|
|
- in parallel. The iterator is passed a callback(truthValue) which must be
|
|
|
- called with a boolean argument once it has completed.
|
|
|
-* `callback(result)` - A callback which is called after all the `iterator`
|
|
|
- functions have finished. Result will be either `true` or `false` depending on
|
|
|
- the values of the async tests.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.every(['file1','file2','file3'], fs.exists, function(result){
|
|
|
- // if result is true then every file exists
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="concat" />
|
|
|
-### concat(arr, iterator, callback)
|
|
|
-
|
|
|
-Applies `iterator` to each item in `arr`, concatenating the results. Returns the
|
|
|
-concatenated list. The `iterator`s are called in parallel, and the results are
|
|
|
-concatenated as they return. There is no guarantee that the results array will
|
|
|
-be returned in the original order of `arr` passed to the `iterator` function.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `arr` - An array to iterate over.
|
|
|
-* `iterator(item, callback)` - A function to apply to each item in `arr`.
|
|
|
- The iterator is passed a `callback(err, results)` which must be called once it
|
|
|
- has completed with an error (which can be `null`) and an array of results.
|
|
|
-* `callback(err, results)` - A callback which is called after all the `iterator`
|
|
|
- functions have finished, or an error occurs. Results is an array containing
|
|
|
- the concatenated results of the `iterator` function.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.concat(['dir1','dir2','dir3'], fs.readdir, function(err, files){
|
|
|
- // files is now a list of filenames that exist in the 3 directories
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="concatSeries" />
|
|
|
-### concatSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-Same as [`concat`](#concat), but executes in series instead of parallel.
|
|
|
-
|
|
|
-
|
|
|
-## Control Flow
|
|
|
-
|
|
|
-<a name="series" />
|
|
|
-### series(tasks, [callback])
|
|
|
-
|
|
|
-Run the functions in the `tasks` array in series, each one running once the previous
|
|
|
-function has completed. If any functions in the series pass an error to its
|
|
|
-callback, no more functions are run, and `callback` is immediately called with the value of the error.
|
|
|
-Otherwise, `callback` receives an array of results when `tasks` have completed.
|
|
|
-
|
|
|
-It is also possible to use an object instead of an array. Each property will be
|
|
|
-run as a function, and the results will be passed to the final `callback` as an object
|
|
|
-instead of an array. This can be a more readable way of handling results from
|
|
|
-[`series`](#series).
|
|
|
-
|
|
|
-**Note** that while many implementations preserve the order of object properties, the
|
|
|
-[ECMAScript Language Specifcation](http://www.ecma-international.org/ecma-262/5.1/#sec-8.6)
|
|
|
-explicitly states that
|
|
|
-
|
|
|
-> The mechanics and order of enumerating the properties is not specified.
|
|
|
-
|
|
|
-So if you rely on the order in which your series of functions are executed, and want
|
|
|
-this to work on all platforms, consider using an array.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `tasks` - An array or object containing functions to run, each function is passed
|
|
|
- a `callback(err, result)` it must call on completion with an error `err` (which can
|
|
|
- be `null`) and an optional `result` value.
|
|
|
-* `callback(err, results)` - An optional callback to run once all the functions
|
|
|
- have completed. This function gets a results array (or object) containing all
|
|
|
- the result arguments passed to the `task` callbacks.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.series([
|
|
|
- function(callback){
|
|
|
- // do some stuff ...
|
|
|
- callback(null, 'one');
|
|
|
- },
|
|
|
- function(callback){
|
|
|
- // do some more stuff ...
|
|
|
- callback(null, 'two');
|
|
|
- }
|
|
|
-],
|
|
|
-// optional callback
|
|
|
-function(err, results){
|
|
|
- // results is now equal to ['one', 'two']
|
|
|
-});
|
|
|
-
|
|
|
-
|
|
|
-// an example using an object instead of an array
|
|
|
-async.series({
|
|
|
- one: function(callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 1);
|
|
|
- }, 200);
|
|
|
- },
|
|
|
- two: function(callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 2);
|
|
|
- }, 100);
|
|
|
- }
|
|
|
-},
|
|
|
-function(err, results) {
|
|
|
- // results is now equal to: {one: 1, two: 2}
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="parallel" />
|
|
|
-### parallel(tasks, [callback])
|
|
|
-
|
|
|
-Run the `tasks` array of functions in parallel, without waiting until the previous
|
|
|
-function has completed. If any of the functions pass an error to its
|
|
|
-callback, the main `callback` is immediately called with the value of the error.
|
|
|
-Once the `tasks` have completed, the results are passed to the final `callback` as an
|
|
|
-array.
|
|
|
-
|
|
|
-It is also possible to use an object instead of an array. Each property will be
|
|
|
-run as a function and the results will be passed to the final `callback` as an object
|
|
|
-instead of an array. This can be a more readable way of handling results from
|
|
|
-[`parallel`](#parallel).
|
|
|
-
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `tasks` - An array or object containing functions to run. Each function is passed
|
|
|
- a `callback(err, result)` which it must call on completion with an error `err`
|
|
|
- (which can be `null`) and an optional `result` value.
|
|
|
-* `callback(err, results)` - An optional callback to run once all the functions
|
|
|
- have completed. This function gets a results array (or object) containing all
|
|
|
- the result arguments passed to the task callbacks.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.parallel([
|
|
|
- function(callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 'one');
|
|
|
- }, 200);
|
|
|
- },
|
|
|
- function(callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 'two');
|
|
|
- }, 100);
|
|
|
- }
|
|
|
-],
|
|
|
-// optional callback
|
|
|
-function(err, results){
|
|
|
- // the results array will equal ['one','two'] even though
|
|
|
- // the second function had a shorter timeout.
|
|
|
-});
|
|
|
-
|
|
|
-
|
|
|
-// an example using an object instead of an array
|
|
|
-async.parallel({
|
|
|
- one: function(callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 1);
|
|
|
- }, 200);
|
|
|
- },
|
|
|
- two: function(callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 2);
|
|
|
- }, 100);
|
|
|
- }
|
|
|
-},
|
|
|
-function(err, results) {
|
|
|
- // results is now equals to: {one: 1, two: 2}
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="parallelLimit" />
|
|
|
-### parallelLimit(tasks, limit, [callback])
|
|
|
-
|
|
|
-The same as [`parallel`](#parallel), only `tasks` are executed in parallel
|
|
|
-with a maximum of `limit` tasks executing at any time.
|
|
|
-
|
|
|
-Note that the `tasks` are not executed in batches, so there is no guarantee that
|
|
|
-the first `limit` tasks will complete before any others are started.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `tasks` - An array or object containing functions to run, each function is passed
|
|
|
- a `callback(err, result)` it must call on completion with an error `err` (which can
|
|
|
- be `null`) and an optional `result` value.
|
|
|
-* `limit` - The maximum number of `tasks` to run at any time.
|
|
|
-* `callback(err, results)` - An optional callback to run once all the functions
|
|
|
- have completed. This function gets a results array (or object) containing all
|
|
|
- the result arguments passed to the `task` callbacks.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="whilst" />
|
|
|
-### whilst(test, fn, callback)
|
|
|
-
|
|
|
-Repeatedly call `fn`, while `test` returns `true`. Calls `callback` when stopped,
|
|
|
-or an error occurs.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `test()` - synchronous truth test to perform before each execution of `fn`.
|
|
|
-* `fn(callback)` - A function which is called each time `test` passes. The function is
|
|
|
- passed a `callback(err)`, which must be called once it has completed with an
|
|
|
- optional `err` argument.
|
|
|
-* `callback(err)` - A callback which is called after the test fails and repeated
|
|
|
- execution of `fn` has stopped.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-var count = 0;
|
|
|
-
|
|
|
-async.whilst(
|
|
|
- function () { return count < 5; },
|
|
|
- function (callback) {
|
|
|
- count++;
|
|
|
- setTimeout(callback, 1000);
|
|
|
- },
|
|
|
- function (err) {
|
|
|
- // 5 seconds have passed
|
|
|
- }
|
|
|
-);
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="doWhilst" />
|
|
|
-### doWhilst(fn, test, callback)
|
|
|
-
|
|
|
-The post-check version of [`whilst`](#whilst). To reflect the difference in
|
|
|
-the order of operations, the arguments `test` and `fn` are switched.
|
|
|
-
|
|
|
-`doWhilst` is to `whilst` as `do while` is to `while` in plain JavaScript.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="until" />
|
|
|
-### until(test, fn, callback)
|
|
|
-
|
|
|
-Repeatedly call `fn` until `test` returns `true`. Calls `callback` when stopped,
|
|
|
-or an error occurs.
|
|
|
-
|
|
|
-The inverse of [`whilst`](#whilst).
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="doUntil" />
|
|
|
-### doUntil(fn, test, callback)
|
|
|
-
|
|
|
-Like [`doWhilst`](#doWhilst), except the `test` is inverted. Note the argument ordering differs from `until`.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="forever" />
|
|
|
-### forever(fn, errback)
|
|
|
-
|
|
|
-Calls the asynchronous function `fn` with a callback parameter that allows it to
|
|
|
-call itself again, in series, indefinitely.
|
|
|
-
|
|
|
-If an error is passed to the callback then `errback` is called with the
|
|
|
-error, and execution stops, otherwise it will never be called.
|
|
|
-
|
|
|
-```js
|
|
|
-async.forever(
|
|
|
- function(next) {
|
|
|
- // next is suitable for passing to things that need a callback(err [, whatever]);
|
|
|
- // it will result in this function being called again.
|
|
|
- },
|
|
|
- function(err) {
|
|
|
- // if next is called with a value in its first parameter, it will appear
|
|
|
- // in here as 'err', and execution will stop.
|
|
|
- }
|
|
|
-);
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="waterfall" />
|
|
|
-### waterfall(tasks, [callback])
|
|
|
-
|
|
|
-Runs the `tasks` array of functions in series, each passing their results to the next in
|
|
|
-the array. However, if any of the `tasks` pass an error to their own callback, the
|
|
|
-next function is not executed, and the main `callback` is immediately called with
|
|
|
-the error.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `tasks` - An array of functions to run, each function is passed a
|
|
|
- `callback(err, result1, result2, ...)` it must call on completion. The first
|
|
|
- argument is an error (which can be `null`) and any further arguments will be
|
|
|
- passed as arguments in order to the next task.
|
|
|
-* `callback(err, [results])` - An optional callback to run once all the functions
|
|
|
- have completed. This will be passed the results of the last task's callback.
|
|
|
-
|
|
|
-
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.waterfall([
|
|
|
- function(callback){
|
|
|
- callback(null, 'one', 'two');
|
|
|
- },
|
|
|
- function(arg1, arg2, callback){
|
|
|
- // arg1 now equals 'one' and arg2 now equals 'two'
|
|
|
- callback(null, 'three');
|
|
|
- },
|
|
|
- function(arg1, callback){
|
|
|
- // arg1 now equals 'three'
|
|
|
- callback(null, 'done');
|
|
|
- }
|
|
|
-], function (err, result) {
|
|
|
- // result now equals 'done'
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-<a name="compose" />
|
|
|
-### compose(fn1, fn2...)
|
|
|
-
|
|
|
-Creates a function which is a composition of the passed asynchronous
|
|
|
-functions. Each function consumes the return value of the function that
|
|
|
-follows. Composing functions `f()`, `g()`, and `h()` would produce the result of
|
|
|
-`f(g(h()))`, only this version uses callbacks to obtain the return values.
|
|
|
-
|
|
|
-Each function is executed with the `this` binding of the composed function.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `functions...` - the asynchronous functions to compose
|
|
|
-
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-function add1(n, callback) {
|
|
|
- setTimeout(function () {
|
|
|
- callback(null, n + 1);
|
|
|
- }, 10);
|
|
|
-}
|
|
|
-
|
|
|
-function mul3(n, callback) {
|
|
|
- setTimeout(function () {
|
|
|
- callback(null, n * 3);
|
|
|
- }, 10);
|
|
|
-}
|
|
|
-
|
|
|
-var add1mul3 = async.compose(mul3, add1);
|
|
|
-
|
|
|
-add1mul3(4, function (err, result) {
|
|
|
- // result now equals 15
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-<a name="seq" />
|
|
|
-### seq(fn1, fn2...)
|
|
|
-
|
|
|
-Version of the compose function that is more natural to read.
|
|
|
-Each following function consumes the return value of the latter function.
|
|
|
-
|
|
|
-Each function is executed with the `this` binding of the composed function.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* functions... - the asynchronous functions to compose
|
|
|
-
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-// Requires lodash (or underscore), express3 and dresende's orm2.
|
|
|
-// Part of an app, that fetches cats of the logged user.
|
|
|
-// This example uses `seq` function to avoid overnesting and error
|
|
|
-// handling clutter.
|
|
|
-app.get('/cats', function(request, response) {
|
|
|
- function handleError(err, data, callback) {
|
|
|
- if (err) {
|
|
|
- console.error(err);
|
|
|
- response.json({ status: 'error', message: err.message });
|
|
|
- }
|
|
|
- else {
|
|
|
- callback(data);
|
|
|
- }
|
|
|
- }
|
|
|
- var User = request.models.User;
|
|
|
- async.seq(
|
|
|
- _.bind(User.get, User), // 'User.get' has signature (id, callback(err, data))
|
|
|
- handleError,
|
|
|
- function(user, fn) {
|
|
|
- user.getCats(fn); // 'getCats' has signature (callback(err, data))
|
|
|
- },
|
|
|
- handleError,
|
|
|
- function(cats) {
|
|
|
- response.json({ status: 'ok', message: 'Cats found', data: cats });
|
|
|
- }
|
|
|
- )(req.session.user_id);
|
|
|
- }
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-<a name="applyEach" />
|
|
|
-### applyEach(fns, args..., callback)
|
|
|
-
|
|
|
-Applies the provided arguments to each function in the array, calling
|
|
|
-`callback` after all functions have completed. If you only provide the first
|
|
|
-argument, then it will return a function which lets you pass in the
|
|
|
-arguments as if it were a single function call.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `fns` - the asynchronous functions to all call with the same arguments
|
|
|
-* `args...` - any number of separate arguments to pass to the function
|
|
|
-* `callback` - the final argument should be the callback, called when all
|
|
|
- functions have completed processing
|
|
|
-
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.applyEach([enableSearch, updateSchema], 'bucket', callback);
|
|
|
-
|
|
|
-// partial application example:
|
|
|
-async.each(
|
|
|
- buckets,
|
|
|
- async.applyEach([enableSearch, updateSchema]),
|
|
|
- callback
|
|
|
-);
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="applyEachSeries" />
|
|
|
-### applyEachSeries(arr, iterator, callback)
|
|
|
-
|
|
|
-The same as [`applyEach`](#applyEach) only the functions are applied in series.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="queue" />
|
|
|
-### queue(worker, concurrency)
|
|
|
-
|
|
|
-Creates a `queue` object with the specified `concurrency`. Tasks added to the
|
|
|
-`queue` are processed in parallel (up to the `concurrency` limit). If all
|
|
|
-`worker`s are in progress, the task is queued until one becomes available.
|
|
|
-Once a `worker` completes a `task`, that `task`'s callback is called.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `worker(task, callback)` - An asynchronous function for processing a queued
|
|
|
- task, which must call its `callback(err)` argument when finished, with an
|
|
|
- optional `error` as an argument.
|
|
|
-* `concurrency` - An `integer` for determining how many `worker` functions should be
|
|
|
- run in parallel.
|
|
|
-
|
|
|
-__Queue objects__
|
|
|
-
|
|
|
-The `queue` object returned by this function has the following properties and
|
|
|
-methods:
|
|
|
-
|
|
|
-* `length()` - a function returning the number of items waiting to be processed.
|
|
|
-* `started` - a function returning whether or not any items have been pushed and processed by the queue
|
|
|
-* `running()` - a function returning the number of items currently being processed.
|
|
|
-* `idle()` - a function returning false if there are items waiting or being processed, or true if not.
|
|
|
-* `concurrency` - an integer for determining how many `worker` functions should be
|
|
|
- run in parallel. This property can be changed after a `queue` is created to
|
|
|
- alter the concurrency on-the-fly.
|
|
|
-* `push(task, [callback])` - add a new task to the `queue`. Calls `callback` once
|
|
|
- the `worker` has finished processing the task. Instead of a single task, a `tasks` array
|
|
|
- can be submitted. The respective callback is used for every task in the list.
|
|
|
-* `unshift(task, [callback])` - add a new task to the front of the `queue`.
|
|
|
-* `saturated` - a callback that is called when the `queue` length hits the `concurrency` limit,
|
|
|
- and further tasks will be queued.
|
|
|
-* `empty` - a callback that is called when the last item from the `queue` is given to a `worker`.
|
|
|
-* `drain` - a callback that is called when the last item from the `queue` has returned from the `worker`.
|
|
|
-* `paused` - a boolean for determining whether the queue is in a paused state
|
|
|
-* `pause()` - a function that pauses the processing of tasks until `resume()` is called.
|
|
|
-* `resume()` - a function that resumes the processing of queued tasks when the queue is paused.
|
|
|
-* `kill()` - a function that empties remaining tasks from the queue forcing it to go idle.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-// create a queue object with concurrency 2
|
|
|
-
|
|
|
-var q = async.queue(function (task, callback) {
|
|
|
- console.log('hello ' + task.name);
|
|
|
- callback();
|
|
|
-}, 2);
|
|
|
-
|
|
|
-
|
|
|
-// assign a callback
|
|
|
-q.drain = function() {
|
|
|
- console.log('all items have been processed');
|
|
|
-}
|
|
|
-
|
|
|
-// add some items to the queue
|
|
|
-
|
|
|
-q.push({name: 'foo'}, function (err) {
|
|
|
- console.log('finished processing foo');
|
|
|
-});
|
|
|
-q.push({name: 'bar'}, function (err) {
|
|
|
- console.log('finished processing bar');
|
|
|
-});
|
|
|
-
|
|
|
-// add some items to the queue (batch-wise)
|
|
|
-
|
|
|
-q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function (err) {
|
|
|
- console.log('finished processing bar');
|
|
|
-});
|
|
|
-
|
|
|
-// add some items to the front of the queue
|
|
|
-
|
|
|
-q.unshift({name: 'bar'}, function (err) {
|
|
|
- console.log('finished processing bar');
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="priorityQueue" />
|
|
|
-### priorityQueue(worker, concurrency)
|
|
|
-
|
|
|
-The same as [`queue`](#queue) only tasks are assigned a priority and completed in ascending priority order. There are two differences between `queue` and `priorityQueue` objects:
|
|
|
-
|
|
|
-* `push(task, priority, [callback])` - `priority` should be a number. If an array of
|
|
|
- `tasks` is given, all tasks will be assigned the same priority.
|
|
|
-* The `unshift` method was removed.
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="cargo" />
|
|
|
-### cargo(worker, [payload])
|
|
|
-
|
|
|
-Creates a `cargo` object with the specified payload. Tasks added to the
|
|
|
-cargo will be processed altogether (up to the `payload` limit). If the
|
|
|
-`worker` is in progress, the task is queued until it becomes available. Once
|
|
|
-the `worker` has completed some tasks, each callback of those tasks is called.
|
|
|
-Check out [this animation](https://camo.githubusercontent.com/6bbd36f4cf5b35a0f11a96dcd2e97711ffc2fb37/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130382f62626330636662302d356632392d313165322d393734662d3333393763363464633835382e676966) for how `cargo` and `queue` work.
|
|
|
-
|
|
|
-While [queue](#queue) passes only one task to one of a group of workers
|
|
|
-at a time, cargo passes an array of tasks to a single worker, repeating
|
|
|
-when the worker is finished.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `worker(tasks, callback)` - An asynchronous function for processing an array of
|
|
|
- queued tasks, which must call its `callback(err)` argument when finished, with
|
|
|
- an optional `err` argument.
|
|
|
-* `payload` - An optional `integer` for determining how many tasks should be
|
|
|
- processed per round; if omitted, the default is unlimited.
|
|
|
-
|
|
|
-__Cargo objects__
|
|
|
-
|
|
|
-The `cargo` object returned by this function has the following properties and
|
|
|
-methods:
|
|
|
-
|
|
|
-* `length()` - A function returning the number of items waiting to be processed.
|
|
|
-* `payload` - An `integer` for determining how many tasks should be
|
|
|
- process per round. This property can be changed after a `cargo` is created to
|
|
|
- alter the payload on-the-fly.
|
|
|
-* `push(task, [callback])` - Adds `task` to the `queue`. The callback is called
|
|
|
- once the `worker` has finished processing the task. Instead of a single task, an array of `tasks`
|
|
|
- can be submitted. The respective callback is used for every task in the list.
|
|
|
-* `saturated` - A callback that is called when the `queue.length()` hits the concurrency and further tasks will be queued.
|
|
|
-* `empty` - A callback that is called when the last item from the `queue` is given to a `worker`.
|
|
|
-* `drain` - A callback that is called when the last item from the `queue` has returned from the `worker`.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-// create a cargo object with payload 2
|
|
|
-
|
|
|
-var cargo = async.cargo(function (tasks, callback) {
|
|
|
- for(var i=0; i<tasks.length; i++){
|
|
|
- console.log('hello ' + tasks[i].name);
|
|
|
- }
|
|
|
- callback();
|
|
|
-}, 2);
|
|
|
-
|
|
|
-
|
|
|
-// add some items
|
|
|
-
|
|
|
-cargo.push({name: 'foo'}, function (err) {
|
|
|
- console.log('finished processing foo');
|
|
|
-});
|
|
|
-cargo.push({name: 'bar'}, function (err) {
|
|
|
- console.log('finished processing bar');
|
|
|
-});
|
|
|
-cargo.push({name: 'baz'}, function (err) {
|
|
|
- console.log('finished processing baz');
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="auto" />
|
|
|
-### auto(tasks, [callback])
|
|
|
-
|
|
|
-Determines the best order for running the functions in `tasks`, based on their
|
|
|
-requirements. Each function can optionally depend on other functions being completed
|
|
|
-first, and each function is run as soon as its requirements are satisfied.
|
|
|
-
|
|
|
-If any of the functions pass an error to their callback, it will not
|
|
|
-complete (so any other functions depending on it will not run), and the main
|
|
|
-`callback` is immediately called with the error. Functions also receive an
|
|
|
-object containing the results of functions which have completed so far.
|
|
|
-
|
|
|
-Note, all functions are called with a `results` object as a second argument,
|
|
|
-so it is unsafe to pass functions in the `tasks` object which cannot handle the
|
|
|
-extra argument.
|
|
|
-
|
|
|
-For example, this snippet of code:
|
|
|
-
|
|
|
-```js
|
|
|
-async.auto({
|
|
|
- readData: async.apply(fs.readFile, 'data.txt', 'utf-8')
|
|
|
-}, callback);
|
|
|
-```
|
|
|
-
|
|
|
-will have the effect of calling `readFile` with the results object as the last
|
|
|
-argument, which will fail:
|
|
|
-
|
|
|
-```js
|
|
|
-fs.readFile('data.txt', 'utf-8', cb, {});
|
|
|
-```
|
|
|
-
|
|
|
-Instead, wrap the call to `readFile` in a function which does not forward the
|
|
|
-`results` object:
|
|
|
-
|
|
|
-```js
|
|
|
-async.auto({
|
|
|
- readData: function(cb, results){
|
|
|
- fs.readFile('data.txt', 'utf-8', cb);
|
|
|
- }
|
|
|
-}, callback);
|
|
|
-```
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `tasks` - An object. Each of its properties is either a function or an array of
|
|
|
- requirements, with the function itself the last item in the array. The object's key
|
|
|
- of a property serves as the name of the task defined by that property,
|
|
|
- i.e. can be used when specifying requirements for other tasks.
|
|
|
- The function receives two arguments: (1) a `callback(err, result)` which must be
|
|
|
- called when finished, passing an `error` (which can be `null`) and the result of
|
|
|
- the function's execution, and (2) a `results` object, containing the results of
|
|
|
- the previously executed functions.
|
|
|
-* `callback(err, results)` - An optional callback which is called when all the
|
|
|
- tasks have been completed. It receives the `err` argument if any `tasks`
|
|
|
- pass an error to their callback. Results are always returned; however, if
|
|
|
- an error occurs, no further `tasks` will be performed, and the results
|
|
|
- object will only contain partial results.
|
|
|
-
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-async.auto({
|
|
|
- get_data: function(callback){
|
|
|
- console.log('in get_data');
|
|
|
- // async code to get some data
|
|
|
- callback(null, 'data', 'converted to array');
|
|
|
- },
|
|
|
- make_folder: function(callback){
|
|
|
- console.log('in make_folder');
|
|
|
- // async code to create a directory to store a file in
|
|
|
- // this is run at the same time as getting the data
|
|
|
- callback(null, 'folder');
|
|
|
- },
|
|
|
- write_file: ['get_data', 'make_folder', function(callback, results){
|
|
|
- console.log('in write_file', JSON.stringify(results));
|
|
|
- // once there is some data and the directory exists,
|
|
|
- // write the data to a file in the directory
|
|
|
- callback(null, 'filename');
|
|
|
- }],
|
|
|
- email_link: ['write_file', function(callback, results){
|
|
|
- console.log('in email_link', JSON.stringify(results));
|
|
|
- // once the file is written let's email a link to it...
|
|
|
- // results.write_file contains the filename returned by write_file.
|
|
|
- callback(null, {'file':results.write_file, 'email':'[email protected]'});
|
|
|
- }]
|
|
|
-}, function(err, results) {
|
|
|
- console.log('err = ', err);
|
|
|
- console.log('results = ', results);
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-This is a fairly trivial example, but to do this using the basic parallel and
|
|
|
-series functions would look like this:
|
|
|
-
|
|
|
-```js
|
|
|
-async.parallel([
|
|
|
- function(callback){
|
|
|
- console.log('in get_data');
|
|
|
- // async code to get some data
|
|
|
- callback(null, 'data', 'converted to array');
|
|
|
- },
|
|
|
- function(callback){
|
|
|
- console.log('in make_folder');
|
|
|
- // async code to create a directory to store a file in
|
|
|
- // this is run at the same time as getting the data
|
|
|
- callback(null, 'folder');
|
|
|
- }
|
|
|
-],
|
|
|
-function(err, results){
|
|
|
- async.series([
|
|
|
- function(callback){
|
|
|
- console.log('in write_file', JSON.stringify(results));
|
|
|
- // once there is some data and the directory exists,
|
|
|
- // write the data to a file in the directory
|
|
|
- results.push('filename');
|
|
|
- callback(null);
|
|
|
- },
|
|
|
- function(callback){
|
|
|
- console.log('in email_link', JSON.stringify(results));
|
|
|
- // once the file is written let's email a link to it...
|
|
|
- callback(null, {'file':results.pop(), 'email':'[email protected]'});
|
|
|
- }
|
|
|
- ]);
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-For a complicated series of `async` tasks, using the [`auto`](#auto) function makes adding
|
|
|
-new tasks much easier (and the code more readable).
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="retry" />
|
|
|
-### retry([times = 5], task, [callback])
|
|
|
-
|
|
|
-Attempts to get a successful response from `task` no more than `times` times before
|
|
|
-returning an error. If the task is successful, the `callback` will be passed the result
|
|
|
-of the successfull task. If all attemps fail, the callback will be passed the error and
|
|
|
-result (if any) of the final attempt.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `times` - An integer indicating how many times to attempt the `task` before giving up. Defaults to 5.
|
|
|
-* `task(callback, results)` - A function which receives two arguments: (1) a `callback(err, result)`
|
|
|
- which must be called when finished, passing `err` (which can be `null`) and the `result` of
|
|
|
- the function's execution, and (2) a `results` object, containing the results of
|
|
|
- the previously executed functions (if nested inside another control flow).
|
|
|
-* `callback(err, results)` - An optional callback which is called when the
|
|
|
- task has succeeded, or after the final failed attempt. It receives the `err` and `result` arguments of the last attempt at completing the `task`.
|
|
|
-
|
|
|
-The [`retry`](#retry) function can be used as a stand-alone control flow by passing a
|
|
|
-callback, as shown below:
|
|
|
-
|
|
|
-```js
|
|
|
-async.retry(3, apiMethod, function(err, result) {
|
|
|
- // do something with the result
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-It can also be embeded within other control flow functions to retry individual methods
|
|
|
-that are not as reliable, like this:
|
|
|
-
|
|
|
-```js
|
|
|
-async.auto({
|
|
|
- users: api.getUsers.bind(api),
|
|
|
- payments: async.retry(3, api.getPayments.bind(api))
|
|
|
-}, function(err, results) {
|
|
|
- // do something with the results
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="iterator" />
|
|
|
-### iterator(tasks)
|
|
|
-
|
|
|
-Creates an iterator function which calls the next function in the `tasks` array,
|
|
|
-returning a continuation to call the next one after that. It's also possible to
|
|
|
-“peek” at the next iterator with `iterator.next()`.
|
|
|
-
|
|
|
-This function is used internally by the `async` module, but can be useful when
|
|
|
-you want to manually control the flow of functions in series.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `tasks` - An array of functions to run.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-var iterator = async.iterator([
|
|
|
- function(){ sys.p('one'); },
|
|
|
- function(){ sys.p('two'); },
|
|
|
- function(){ sys.p('three'); }
|
|
|
-]);
|
|
|
-
|
|
|
-node> var iterator2 = iterator();
|
|
|
-'one'
|
|
|
-node> var iterator3 = iterator2();
|
|
|
-'two'
|
|
|
-node> iterator3();
|
|
|
-'three'
|
|
|
-node> var nextfn = iterator2.next();
|
|
|
-node> nextfn();
|
|
|
-'three'
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="apply" />
|
|
|
-### apply(function, arguments..)
|
|
|
-
|
|
|
-Creates a continuation function with some arguments already applied.
|
|
|
-
|
|
|
-Useful as a shorthand when combined with other control flow functions. Any arguments
|
|
|
-passed to the returned function are added to the arguments originally passed
|
|
|
-to apply.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `function` - The function you want to eventually apply all arguments to.
|
|
|
-* `arguments...` - Any number of arguments to automatically apply when the
|
|
|
- continuation is called.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-// using apply
|
|
|
-
|
|
|
-async.parallel([
|
|
|
- async.apply(fs.writeFile, 'testfile1', 'test1'),
|
|
|
- async.apply(fs.writeFile, 'testfile2', 'test2'),
|
|
|
-]);
|
|
|
-
|
|
|
-
|
|
|
-// the same process without using apply
|
|
|
-
|
|
|
-async.parallel([
|
|
|
- function(callback){
|
|
|
- fs.writeFile('testfile1', 'test1', callback);
|
|
|
- },
|
|
|
- function(callback){
|
|
|
- fs.writeFile('testfile2', 'test2', callback);
|
|
|
- }
|
|
|
-]);
|
|
|
-```
|
|
|
-
|
|
|
-It's possible to pass any number of additional arguments when calling the
|
|
|
-continuation:
|
|
|
-
|
|
|
-```js
|
|
|
-node> var fn = async.apply(sys.puts, 'one');
|
|
|
-node> fn('two', 'three');
|
|
|
-one
|
|
|
-two
|
|
|
-three
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="nextTick" />
|
|
|
-### nextTick(callback)
|
|
|
-
|
|
|
-Calls `callback` on a later loop around the event loop. In Node.js this just
|
|
|
-calls `process.nextTick`; in the browser it falls back to `setImmediate(callback)`
|
|
|
-if available, otherwise `setTimeout(callback, 0)`, which means other higher priority
|
|
|
-events may precede the execution of `callback`.
|
|
|
-
|
|
|
-This is used internally for browser-compatibility purposes.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `callback` - The function to call on a later loop around the event loop.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-var call_order = [];
|
|
|
-async.nextTick(function(){
|
|
|
- call_order.push('two');
|
|
|
- // call_order now equals ['one','two']
|
|
|
-});
|
|
|
-call_order.push('one')
|
|
|
-```
|
|
|
-
|
|
|
-<a name="times" />
|
|
|
-### times(n, callback)
|
|
|
-
|
|
|
-Calls the `callback` function `n` times, and accumulates results in the same manner
|
|
|
-you would use with [`map`](#map).
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `n` - The number of times to run the function.
|
|
|
-* `callback` - The function to call `n` times.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-// Pretend this is some complicated async factory
|
|
|
-var createUser = function(id, callback) {
|
|
|
- callback(null, {
|
|
|
- id: 'user' + id
|
|
|
- })
|
|
|
-}
|
|
|
-// generate 5 users
|
|
|
-async.times(5, function(n, next){
|
|
|
- createUser(n, function(err, user) {
|
|
|
- next(err, user)
|
|
|
- })
|
|
|
-}, function(err, users) {
|
|
|
- // we should now have 5 users
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-<a name="timesSeries" />
|
|
|
-### timesSeries(n, callback)
|
|
|
-
|
|
|
-The same as [`times`](#times), only the iterator is applied to each item in `arr` in
|
|
|
-series. The next `iterator` is only called once the current one has completed.
|
|
|
-The results array will be in the same order as the original.
|
|
|
-
|
|
|
-
|
|
|
-## Utils
|
|
|
-
|
|
|
-<a name="memoize" />
|
|
|
-### memoize(fn, [hasher])
|
|
|
-
|
|
|
-Caches the results of an `async` function. When creating a hash to store function
|
|
|
-results against, the callback is omitted from the hash and an optional hash
|
|
|
-function can be used.
|
|
|
-
|
|
|
-The cache of results is exposed as the `memo` property of the function returned
|
|
|
-by `memoize`.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `fn` - The function to proxy and cache results from.
|
|
|
-* `hasher` - Tn optional function for generating a custom hash for storing
|
|
|
- results. It has all the arguments applied to it apart from the callback, and
|
|
|
- must be synchronous.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-var slow_fn = function (name, callback) {
|
|
|
- // do something
|
|
|
- callback(null, result);
|
|
|
-};
|
|
|
-var fn = async.memoize(slow_fn);
|
|
|
-
|
|
|
-// fn can now be used as if it were slow_fn
|
|
|
-fn('some name', function () {
|
|
|
- // callback
|
|
|
-});
|
|
|
-```
|
|
|
-
|
|
|
-<a name="unmemoize" />
|
|
|
-### unmemoize(fn)
|
|
|
-
|
|
|
-Undoes a [`memoize`](#memoize)d function, reverting it to the original, unmemoized
|
|
|
-form. Handy for testing.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `fn` - the memoized function
|
|
|
-
|
|
|
-<a name="log" />
|
|
|
-### log(function, arguments)
|
|
|
-
|
|
|
-Logs the result of an `async` function to the `console`. Only works in Node.js or
|
|
|
-in browsers that support `console.log` and `console.error` (such as FF and Chrome).
|
|
|
-If multiple arguments are returned from the async function, `console.log` is
|
|
|
-called on each argument in order.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `function` - The function you want to eventually apply all arguments to.
|
|
|
-* `arguments...` - Any number of arguments to apply to the function.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-var hello = function(name, callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, 'hello ' + name);
|
|
|
- }, 1000);
|
|
|
-};
|
|
|
-```
|
|
|
-```js
|
|
|
-node> async.log(hello, 'world');
|
|
|
-'hello world'
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="dir" />
|
|
|
-### dir(function, arguments)
|
|
|
-
|
|
|
-Logs the result of an `async` function to the `console` using `console.dir` to
|
|
|
-display the properties of the resulting object. Only works in Node.js or
|
|
|
-in browsers that support `console.dir` and `console.error` (such as FF and Chrome).
|
|
|
-If multiple arguments are returned from the async function, `console.dir` is
|
|
|
-called on each argument in order.
|
|
|
-
|
|
|
-__Arguments__
|
|
|
-
|
|
|
-* `function` - The function you want to eventually apply all arguments to.
|
|
|
-* `arguments...` - Any number of arguments to apply to the function.
|
|
|
-
|
|
|
-__Example__
|
|
|
-
|
|
|
-```js
|
|
|
-var hello = function(name, callback){
|
|
|
- setTimeout(function(){
|
|
|
- callback(null, {hello: name});
|
|
|
- }, 1000);
|
|
|
-};
|
|
|
-```
|
|
|
-```js
|
|
|
-node> async.dir(hello, 'world');
|
|
|
-{hello: 'world'}
|
|
|
-```
|
|
|
-
|
|
|
----------------------------------------
|
|
|
-
|
|
|
-<a name="noConflict" />
|
|
|
-### noConflict()
|
|
|
-
|
|
|
-Changes the value of `async` back to its original value, returning a reference to the
|
|
|
-`async` object.
|