在对象中绑定函数调用

Question

目标：在对象中定义的函数被调用时执行函数

例子：

var obj = {
    endUpdate: function(){
       ... (async stuff from library, cannot modify this code)
    }
}

我想写这样的东西，以了解何时调用了 endUpdate

obj.on('endUpdate', function(){
    // do stuff here when "endUpdate" in above object is called
})

Answer 1

你可以像这样很容易地创建订阅者函数

var obj = {
   listeners: {
      endUpdate: []
   },
   on: function(name, callbackFn){
      this.listeners[name].push(callbackFn);
   },
   runListeners: function(name) {
      this.listeners[name].forEach((fn) => fn());
   },
   endUpdate: async function(){
       await someStuffFromLib();
       this.runListeners('endUpdate');
   }
}

否则你可以增强对象和链异步功能，只要你一直保持链

 var obj = {
   endUpdate: function(){
      const thisIsAPromise = someStuffFromLib();
      return thisIsAPromise;
   }
}

const newObj = {
    endUpdate: (...args) => obj.endUpdate(...args).then(
                (result) => { console.log(result)})
}