redirect-by-region/index.js

window.regions = document.querySelectorAll('link[rel=region]');
window.regionMap = {};
window.regions.forEach(function(item) { 
    window.regionMap[item.attributes.regionflag.value] = item.attributes.href.value;
});
let xhr = new XMLHttpRequest();
xhr.open("GET", "https://api.ipify.org/?format=json");
xhr.addEventListener("loadend", async function (e){
    let responseObj = JSON.parse(this.response);
    let ip = responseObj.ip;
    let regionData = await ipToRegion(ip);
    if (window.regionMap[regionData.geoplugin_countryName]) {
        window.location.href = window.regionMap[regionData.geoplugin_countryName]
    }
});
xhr.send();
async function ipToRegion(ip) {
    const response = await fetch(`http://www.geoplugin.net/json.gp?ip=${ip}`);
    const data = await response.json();
    return data;
}