Why Are My AJAX Function Return Values Empty?

The Enigma of Unreturned Variable in AJAX Function

In the realm of web applications, it's common to modularize JavaScript code into separate files to enhance organization and maintainability. However, this transition can introduce enigmatic issues, such as variables seemingly disappearing when returned from AJAX functions.

Problem:

After splitting a framework into multiple files, a developer encounters an issue where a variable returned from an AJAX function remains empty. Despite the data being present in the JS file, it fails to return upon execution. The code under scrutiny:

function get_data(data, destination) {
  ...
  if (data) {
    return data;
  }
}

var test = get_data(data, destination);

Cause:

Asynchronous nature of AJAX calls is the culprit. An AJAX call executes in the background, meaning the code continues to execute without waiting for the response. Consequently, the get_data function returns before the AJAX call completes, resulting in an empty test variable.

Solution:

To resolve this issue, it's necessary to use a callback function to handle the AJAX response. A callback function is invoked when the AJAX call is complete, allowing you to access the returned data.

function get_data(data, destination, callback) {
  ...
  if (data && callback) {
    callback(data);
  }
}

get_data(data, destination, function(test) {
  notice(test);
});

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