javascript - 具有复杂计算的异步回调Javascript

Question

我正在尝试异步进行一些计算，并在回调中获取计算结果。

function customWithCallBack(callback) {
	//Complex logic calculation that takes time.
  	callback();
}

function actualCallBack() {
	console.log("This is callback called after certain event");
}


console.log("First");
customWithCallBack(actualCallBack);
console.log("Second");

//Required Output
First
Second
This is callback called after certain event.


//Actual Output
First
This is callback called after certain event
Second

如何才能达到所需的输出？那是第一个“First is print”。然后，“第二”。最后在复杂逻辑完成后调用回调进行打印“这是在特定事件之后调用的回调”。除了网络请求和I/O操作之外，是否可以进行复杂的计算？

Answer 1

function customWithCallBack(callback) {
	//Complex logic calculation that takes time.
     setTimeout(function(){ callback(); }, 100);
  	
}

function actualCallBack() {
	console.log("This is callback called after certain event");
}


console.log("First");
customWithCallBack(actualCallBack);
console.log("Second");