How Can I Ensure All jQuery Ajax Requests Complete Before Continuing Function Execution?

How to Pause Function Execution Until jQuery Ajax Requests Complete

When executing multiple jQuery Ajax requests within a function, it can become necessary to ensure that all requests have completed before proceeding to the next action. This is especially crucial to prevent data inconsistencies or race conditions.

To address this issue, jQuery introduces the powerful .when() function. This function allows developers to specify multiple Deferred objects as arguments and executes a callback function when all of them resolve.

Consider the following example where you initiate four Ajax requests:

function ajax1() {
    return $.ajax({ /* Ajax request parameters */ });
}

To wait for all four requests to complete before proceeding, you can utilize .when() as follows:

$.when(ajax1(), ajax2(), ajax3(), ajax4()).done(function(a1, a2, a3, a4){
    // This code will execute when all Ajax requests resolve.
    // a1, a2, a3, and a4 contain response data and status.
});

This approach ensures that subsequent actions are not executed until all Ajax requests have successfully completed, reducing the risk of errors and data integrity issues.

For situations where you have a variable number of Ajax requests, the argument list can be generated dynamically. However, this requires a slightly more intricate approach.

Additionally, the .when() function returns a jQuery Promise object that encompasses all the Ajax queries. This provides further control over the failure modes by allowing you to specify custom success and failure handlers using .then() and .fail().

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