javascript-obfuscator/src/node-transformers/preparing-transformers/CommentsTransformer.ts

import { inject, injectable, } from 'inversify';
import { ServiceIdentifiers } from '../../container/ServiceIdentifiers';

import * as ESTree from 'estree';

import { IOptions } from '../../interfaces/options/IOptions';
import { IRandomGenerator } from '../../interfaces/utils/IRandomGenerator';
import { IVisitor } from '../../interfaces/node-transformers/IVisitor';

import { AbstractNodeTransformer } from '../AbstractNodeTransformer';
import { NodeGuards } from '../../node/NodeGuards';

@injectable()
export class CommentsTransformer extends AbstractNodeTransformer {
    /**
     * @type {string[]}
     */
    private static preservedWords: string[] = ['@license', '@preserve', 'javascript-obfuscator'];

    /**
     * @param {IRandomGenerator} randomGenerator
     * @param {IOptions} options
     */
    constructor (
        @inject(ServiceIdentifiers.IRandomGenerator) randomGenerator: IRandomGenerator,
        @inject(ServiceIdentifiers.IOptions) options: IOptions
    ) {
        super(randomGenerator, options);
    }

    /**
     * @return {IVisitor}
     */
    public getVisitor (): IVisitor {
        return {
            enter: (node: ESTree.Node, parentNode: ESTree.Node | null) => {
                if (parentNode && NodeGuards.isNodeWithComments(node)) {
                    return this.transformNode(node, parentNode);
                }
            }
        };
    }

    /**
     * Removes all comments from node except comments that contain
     * `@license`, `@preserve` or `javascript-obfuscator` words
     *
     * @param {Node} node
     * @param {Node} parentNode
     * @returns {NodeGuards}
     */
    public transformNode (node: ESTree.Node, parentNode: ESTree.Node): ESTree.Node {
        if (node.leadingComments) {
            node.leadingComments = this.transformComments(node.leadingComments);
        }

        if (node.trailingComments) {
            node.trailingComments = this.transformComments(node.trailingComments);
        }

        return node;
    }

    /**
     * @param {Comment[]} comments
     * @returns {Comment[]}
     */
    private transformComments (comments: ESTree.Comment[]): ESTree.Comment[] {
        return comments.filter((comment: ESTree.Comment) =>
            CommentsTransformer.preservedWords
                .some((availableWord: string) => comment.value.includes(availableWord))
        );
    }
}