javascript - 猴子补丁 Promise 构造函数

Question

作为练习，我尝试对 Promise 构造函数进行猴子修补，如下所示:

const pconstructor = global.Promise;
global.Promise = function (fn1) {
  this.foo = 'bar';
  pconstructor.call(this,fn1);
};

global.Promise.resolve = pconstructor.resolve;

然而，当我调用时出现错误

Promise.resolve();

=>

TypeError: [object Object] is not a promise

有人知道如何正确地对这样的构造函数进行猴子修补吗？

Answer 1

我建议只写一个 Promise 的子类:

const global = window; // (in browser...)


const OldPromise = global.Promise; 
global.Promise = class Promise extends OldPromise {
  constructor(executor) {
    // do whatever you want here, but must call super()
    console.log('hello, promise');

    super(executor); // call native Promise constructor
  }
};

Promise.resolve(); // prints: "hello, promise"

当尝试对这样的类进行猴子修补时，这会处理幕后的所有细节。