Скачать или смотреть Understanding Why setAttribute Doesn't Apply Class to li Elements

Discover common issues with setting class attributes in JavaScript and learn how to properly manipulate DOM elements for effective styling.
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This video is based on the question https://stackoverflow.com/q/74443937/ asked by the user 'David-JSON' ( https://stackoverflow.com/u/20183342/ ) and on the answer https://stackoverflow.com/a/74443996/ provided by the user 'Maniraj Murugan' ( https://stackoverflow.com/u/7785337/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Why Your setAttribute Method Might Not Be Working as Expected

When you embark on learning DOM Manipulation, you are bound to encounter a few hurdles along the way. One such common issue is when the setAttribute method seems ineffective, specifically when trying to set a class for an li element in JavaScript. In this blog, we will unpack this problem and offer a clear solution.

Problem Overview

Imagine you have written some JavaScript code to manipulate a list on your webpage. You want to dynamically create an li element, set its class, and expect it to inherit certain styles. Unfortunately, the expected styles—like fontSize—aren't being applied to your new li element. This can be confusing for beginners, especially when they’re eager to see their code in action.

Example Code

Let's take a look at a code snippet to illustrate the problem:

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

In the code above, you create a new li element, set its class to list-items, and it should reflect the CSS styles associated with that class. However, the expected fontSize isn't showing up.

Solution Breakdown

Step 1: Remove Inline Style Setting

One key insight in troubleshooting this issue is to realize you should not set the font size inline for each existing li inside a loop. Instead, define a separate CSS class to manage the styling, making your code cleaner and ensuring that any element with this class gets the intended styles.

CSS Example

You can add the following CSS to define the styling for your list items:

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

Step 2: Properly Append the li Element

Once you create your li element, ensure it's appended to the ul after you've set its class. This ensures that the new element is picked up correctly by the CSS styles associated with .list-items.

Updated JavaScript Example

Here’s an updated version of the JavaScript code:

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

Summary

By understanding these basic principles of DOM manipulation, you can effectively troubleshoot and resolve issues related to setting classes on new elements. Remember, relying on CSS for style management not only makes your code cleaner but also ensures consistent styling across elements.

With the above-simplified steps, you can create dynamic elements that adopt the intended styles seamlessly.

Now, go ahead and give this solution a try, and watch your list come to life with the right fonts!