How can I create an Asynchronous function in Javascript?

Check out this code :

<a href="#" id="link">Link</a>
<span>Moving</span>

$('#link').click(function () {
    console.log("Enter");
    $('#link').animate({ width: 200 }, 2000, function() {
         console.log("finished");            
    });    
    console.log("Exit");    
});

As you can see in the console, the "animate" function is asynchronous, and it "fork"s the flow of the event handler block code. In fact :

$('#link').click(function () {
    console.log("Enter");
    asyncFunct();
    console.log("Exit");    
});

function asyncFunct() {
    console.log("finished");
}

follow the flow of the block code!

If I wish to create my function asyncFunct() { } with this behaviour, how can I do it with javascript/jquery? I think there is a strategy without the use of setTimeout() ​

You cannot make a truly custom asynchronous function. You'll eventually have to leverage on a technology provided natively, such as:

• setInterval
• setTimeout
• requestAnimationFrame
• XMLHttpRequest
• WebSocket
• Worker
• Some HTML5 APIs such as the File API, Web Database API
• Technologies that support onload
• ... many others

In fact, for the animation jQuery uses setInterval.

You can use a timer:

setTimeout( yourFn, 0 );

(where yourFn is a reference to your function)

or, with Lodash:

_.defer( yourFn );

Defers invoking the func until the current call stack has cleared. Any additional arguments are provided to func when it's invoked.

here you have simple solution (other write about it) http://www.benlesh.com/2012/05/calling-javascript-function.html

And here you have above ready solution:

function async(your_function, callback) {
    setTimeout(function() {
        your_function();
        if (callback) {callback();}
    }, 0);
}

TEST 1 (may output '1 x 2 3' or '1 2 x 3' or '1 2 3 x'):

console.log(1);
async(function() {console.log('x')}, null);
console.log(2);
console.log(3);

TEST 2 (will always output 'x 1'):

async(function() {console.log('x');}, function() {console.log(1);});

This function is executed with timeout 0 - it will simulate asynchronous task