How to Use Data from ajax.done to Stop a While Loop in JavaScript

Discover how to properly manage asynchronous calls in JavaScript and effectively break out of loops when using `ajax.done`. Learn practical examples and tips for better coding practices.
---
This video is based on the question https://stackoverflow.com/q/72219108/ asked by the user 'nkosi.nuz' ( https://stackoverflow.com/u/12994396/ ) and on the answer https://stackoverflow.com/a/72219536/ provided by the user 'trincot' ( https://stackoverflow.com/u/5459839/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to use data from an ajax.done to stop a while loop

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Use Data from ajax.done to Stop a While Loop in JavaScript

JavaScript is a powerful tool for web development, and when coupled with jQuery's AJAX capabilities, it can perform even more advanced tasks. However, developers often run into issues with asynchronous calls and loops. One common problem is wanting to stop a while loop based on data retrieved from an AJAX call. This guide will guide you through resolving this issue effectively.

Understanding the Problem

In many cases, developers may find themselves in a while loop attempting to call an AJAX request repeatedly until a certain condition is met based on the response. Here's a basic example:

[[See Video to Reveal this Text or Code Snippet]]

Why This Approach Fails

The issue with the above code lies in how JavaScript handles asynchronous functions:

Infinite Loop: The while(true) construct continuously runs, preventing any other code from executing, including the callback function that would process the AJAX response.

Scope of break: The break statement is not within an actual loop because it is inside of a function. Thus, it has no effect on the while loop.

Event Queue Blockage: Since the loop is perpetually executing, it doesn’t allow for the event queue to process the AJAX response.

The Solution

To properly handle AJAX calls within a loop, we need to refactor the code to utilize a recursive function instead of a conventional while loop. Below is an example demonstrating how to accomplish this:

Using Recursion Rather Than a Loop

[[See Video to Reveal this Text or Code Snippet]]

Explanation: In this code, after the AJAX call is made, the callback function checks the data. If it doesn’t meet the break condition, it calls the loop function again to make another AJAX request.

Modern Approach: Using fetch API with async/await

In current JavaScript practice, using Fetch API along with async functions can provide an even cleaner solution. Here's how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Explanation: This version of the code introduces an asynchronous function that runs indefinitely until the condition is met. Utilizing await pauses the execution until the promise is fulfilled, allowing data from the AJAX call to be processed correctly.

Conclusion

Stopping a loop based on the response from an AJAX call in JavaScript may seem tricky, but with a clear understanding of asynchronous programming, it's straightforward. By avoiding the while(true) construct and embracing recursion or modern async/await functionality, developers can efficiently manage AJAX calls and their responses.

Employing these techniques not only resolves the issue but also enhances the readability and maintainability of your code. Happy coding!