Скачать или смотреть Fixing the JQuery/Ajax Issue: HTML Loads Only Once

Learn how to resolve the common issue of an AJAX call in jQuery that updates HTML content only once by organizing your AJAX call correctly for real-time data display.
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This video is based on the question https://stackoverflow.com/q/63633457/ asked by the user 'Aarlaneth' ( https://stackoverflow.com/u/13535097/ ) and on the answer https://stackoverflow.com/a/63633573/ provided by the user 'David' ( https://stackoverflow.com/u/328193/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing the JQuery/Ajax Issue: HTML Loads Only Once

When building a dynamic web application, the ability to update content without reloading the page is crucial. Using JQuery and AJAX, we can easily make our applications respond to real-time updates. However, many developers encounter an issue where the AJAX call updates HTML only once, leaving subsequent data fetching ineffective.

In this guide, we will dive into this problem and explore a clear solution to ensure your content is updated as intended.

The Problem

The common scenario involves setting up an AJAX call that fetches data from a database every few seconds. In your case, when the AJAX call is made for the first time, the HTML content is updated successfully. However, on subsequent calls made, although the AJAX request captures new data, the HTML remains unchanged. This renders the application unable to display live updates, which is the main goal.

Identifying the Source of the Problem

In your case, the jQuery code looks like this:

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

Here, the self variable holds a reference to the target DOM element. The issue arises within the setTimeout(update, 10000); line, where the context of this changes. On subsequent calls to update(), the value of this does not refer to the expected DOM element anymore.

The Solution: Streamlined AJAX Call

To overcome this problem, it’s important to clarify the structure of the AJAX calls and enhance it for better functionality. The recommendation is to create a standalone function that can handle the AJAX request independently and invoke this function on a set interval.

Revised AJAX Implementation

Here’s the updated implementation:

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

Breakdown of Changes

Function Declaration: The update() function is declared independently, making it easier to manage.

Using setInterval: This replaces setTimeout, making sure the update function is called on a regular interval, ensuring each function call has its own context.

Maintaining self Reference: Inside the each() method, self consistently points to the correct DOM element, allowing reliable manipulation of the HTML content each time new data is fetched.

Conclusion

By restructuring your AJAX calls as demonstrated, you ensure that the page reflects real-time updates accurately. This solution is generalized enough to apply to similar scenarios, providing a solid approach to dynamically updating HTML content without running into scope issues.

With this method, your web application will no longer be stuck showing the same old data, and it will effectively display new entries as they arrive. Happy coding!