设置回调函数以在javascript中返回值

Question

Here is my code:

function render(){
    var el;
    setTimeout(function(){
      func();
    },1000);
    return el;
  }

function func(){
    //do something here;
}

setTimeout is async, so el will be returned before execute func.I want to return el after calling func, how should I write the callback function?

Answer 1

use a callback - a function that el will be passed to:

function render(callback){
    var el;
    setTimeout(function(){
      func();
      callback(el);
    },1000);
  }

function func(){
    //do something here;
}

function elReady(el){
    // use `el`
}

So now you can use render(elReady) .