Object.assign Polyfill (For Wechat) #453
Description
WeChat is a popular chat app in China. On Android it embeds Tecent's custom Webkit browser "X5". This browser requires polyfill for Object.assign.
Maybe it would be nice to have a more declarative way to add polyfills. Right now I used next.conig.js to modify the main.js entry:
// next.config.js
module.exports = {
cdn: false,
webpack: (cfg, { dev }) => {
// prepend polyfill
const main = cfg.entry["main.js"]
cfg.entry["main.js"] = [require.resolve(__dirname + "/polyfill"), main]
// console.log("entries", cfg.entry)
return cfg
}
}Where polyfill.js is the following (note that the feature detection has to use string concat to prevent babel from transforming it to its own assign):
if (typeof Object["ass"+"ign"] != 'function') {
Object.assign = function (target, varArgs) { // .length of function is 2
'use strict';
if (target == null) { // TypeError if undefined or null
throw new TypeError('Cannot convert undefined or null to object');
}
var to = Object(target);
for (var index = 1; index < arguments.length; index++) {
var nextSource = arguments[index];
if (nextSource != null) { // Skip over if undefined or null
for (var nextKey in nextSource) {
// Avoid bugs when hasOwnProperty is shadowed
if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
to[nextKey] = nextSource[nextKey];
}
}
}
}
return to;
};
}