Is It Possible to Define jQuery AJAX Success Callback Functions Externally?

Defining Success Callback Functions for jQuery AJAX

When retrieving data from a server using jQuery AJAX, developers often define the success callback function within the .ajax() block. However, is it possible to define the callback function externally?

External Callback Function

The provided code snippet attempts to define the success callback function outside the .ajax() block:

var dataFromServer;  //declare the variable first

function getData() {
    $.ajax({
        url : 'example.com',
        type: 'GET',
        success : handleData(dataFromServer)
    })
}

function handleData(data) {
    alert(data);
    //do some stuff
}

Recommendation: Use Deferred Objects

While the code snippet may technically work, it is no longer recommended to define the success callback outside the .ajax() block. Instead, use deferred objects:

function getData() {
    return $.ajax({
        url : 'example.com',
        type: 'GET'
    });
}

function handleData(data /* , textStatus, jqXHR */ ) {
    alert(data);
    //do some stuff
}

getData().done(handleData);

Deferred objects provide several advantages:

• Decoupling: They separate callback handling from AJAX handling, allowing for easier maintenance.
• Multiple Callbacks: Deferred objects support adding multiple success and error callbacks.
• Synchronization: They enable easy synchronization of multiple asynchronous events, such as AJAX calls and timers.

Using deferred objects offers greater flexibility and control over AJAX callback handling, making it a more robust and modern approach.

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