如何等待未知调用方调用函数？

Question

我有一个回调函数，它被我无法控制的其他对象调用。我需要等到这个回调函数被调用，我不在乎是谁调用的。

var successFunc = function() {
    // do stuff
}

myObject.onSuccess = successFunc;

// hang on until successFunc is called...

我找到了这个黑客的解决方法，但它很糟糕：

var completed = false;

var successFunc = () => {
    // do stuff
    completed = true;
}

myObject.onSuccess = successFunc;

while (!completed) {
    sleep(200); // sleeps for 200 ms
}

Answer 1

尝试settimeout函数

setTimeout(() => {
        
      }, timeout);

Answer 2

您可以使用wait/async：

https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Operators/await

var myObject = {
    promiseCreation() {
      return new Promise(resolve => {
        setTimeout(() => {
          resolve(true);
        }, 2000);
      });
    }
}

var successFunc = () => {
    completed = true;
    console.log('win');
};

myObject.onSuccess = successFunc;

var asyncfunc = async () => {
    var test = await myObject.promiseCreation();
    //do thing after promise resolved
    myObject.onSuccess();
}

asyncfunc();

Answer 3

创建一个promise，以某种方式将其解决函数作为回调传递给未知调用方，监听promise的解决方案：

let callback;
const promise = new Promise(r => callback = r);

promise.then(() => console.log('unknown caller called'));

setTimeout(function unknownCaller() {
    console.log('randomly calling back');
    callback();
}, Math.random() * 5000);