Javascript - 返回值或使用回调函数

Question

I am curious what is considered the better style/the correct way to do something.

In javascript, I could do the following:

function one() {
    two(param, function(ans){
        // do more work
    });
}

function two(param, callback) {
    var answer;
    //do work
    callback(answer);
}

but I could have a similar result by simply returning the answer:

function one() {
    var ans = two(param);
    // do more work
}

function two(param, callback) {
    var answer;
    //do work
    return answer;
}

I think that if all you need is "answer" then it is probably better to use the second version and just return that value rather than passing a callback function as a parameter, etc. - is my thinking correct? Any ideas on the relative performance of the two? Again, I would expect the return version to be better performance-wise.

Answer 1

Generally a callback function is used when the function you are calling will be performing an asynchronous event (such as making an AJAX call) that will be done in a non-blocking fashion.

Non-blocking means that once you call that function, your code will continue on to the next statement BEFORE the function you just called has completed its work. Hence the callback function, in which you put code that you want to be executed AFTER the non-blocking function has completed.

I would recommend returning answer directly from two rather then implementing a callback. Too many callbacks can lead to what is known as the Callback Pyramid

Answer 2

You should use the return.

Callback are suitable when you perform asynchronous actions, otherwise they're useless overhead.

Answer 3

You should definitely just use return. Callbacks are meant for when you would like some customized code to be executed after the completion of a function or an asynchronous event such as an Ajax call.