Скачать или смотреть How to Use jQuery to Find an ID within a List

Learn how to effectively use `jQuery` to select elements by class and retrieve their IDs from a list. This guide breaks down common mistakes and provides a clear solution with step-by-step instructions.
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This video is based on the question https://stackoverflow.com/q/62398719/ asked by the user 'Silverfin' ( https://stackoverflow.com/u/5603007/ ) and on the answer https://stackoverflow.com/a/62398799/ provided by the user 'Nick' ( https://stackoverflow.com/u/9473764/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use jQuery to Find an ID within a List

Introduction

If you're working with jQuery, you might encounter situations where you need to select specific elements within a list based on their attributes. One common scenario is when you want to find an element that has a certain class (like active) and retrieve its ID.

In this guide, we'll address a common issue: trying to select an ID within a list using jQuery's .find() method and understanding why it might not yield the expected results.

The Problem

Consider the following HTML structure of a list of tabs. The first tab has an active class:

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

If you try to use the following jQuery code to find the ID of the active tab when clicking the second tab:

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

You'll find that activeTab results in undefined, which can be quite frustrating!

The Solution

Understanding the Issues

Incorrect Use of .find(): The .find() method searches for descendants of the selected element. Since the selector $('ul.parcel-tabs li a') already targets the <a> elements, using .find('.active') will not yield the desired result, as the active class is on the same level.

Using .data() Instead of .attr(): When trying to retrieve an element's ID, the correct method to use is .attr('id'), not .data('id'), because the ID is an attribute of the element, not a data value.

The Correct Code

To appropriately select the ID of the active tab, we can simply change the selector to target the active class directly:

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

Complete Example

Here's the complete code incorporating the fixes:

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

Conclusion

By understanding how to properly select elements and retrieve their attributes using jQuery, you can eliminate errors and work more efficiently. Remember that selecting the right elements requires careful consideration of how jQuery traverses the DOM. By following the guidelines presented in this post, you can easily find IDs within lists using jQuery.

Now you're ready to implement these techniques effectively in your own projects!