Скачать или смотреть How to Conditionally Add Classes in JavaScript Templates

Learn how to add classes conditionally in JavaScript templates, utilizing both string concatenation and template literals for enhanced readability and functionality.
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This video is based on the question https://stackoverflow.com/q/64371086/ asked by the user 'TamilRoja' ( https://stackoverflow.com/u/8001892/ ) and on the answer https://stackoverflow.com/a/64371182/ provided by the user 'Rory McCrossan' ( https://stackoverflow.com/u/519413/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Conditional Class Addition in JavaScript Templates

In the world of web development, there are times when you need to modify the classes of your HTML elements based on certain conditions. This flexibility can help you change styles dynamically, optimize user experiences, and enhance the look and feel of your web applications. In this guide, we’ll address a common question on how to add classes conditionally in JavaScript templates.

The Problem

Imagine you have a JavaScript function that generates HTML dynamically, depending on some data you receive. You want to assign a specific class to a <div> based on whether the data matches a particular value. For instance, if the data equals sampleData, you would like the <div> to have the class sample_class; otherwise, it should take on the class test_class.

Here is the initial attempt at the solution:

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

At first glance, this code doesn’t seem to work as intended. Let's delve into how we can correct it.

The Solution

Using String Concatenation

The initial mistake is in how string concatenation is handled. Instead of embedding the condition directly in the string, we can assemble the string piece by piece. Here’s how:

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

Breaking it down:

We're using + to concatenate the different parts of the string.

We evaluate the condition (data == sampleData) to determine which class name should be included.

The class attribute itself is surrounded by double quotes to ensure proper HTML structure.

Using Template Literals

Alternatively, if you are using ES6 and above, you can take advantage of template literals, which allow for easier string formatting. Here’s how you can rewrite the previous code using backticks:

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

Advantages of Template Literals:

Readability: Template literals allow for a cleaner, more readable code structure.

Multi-line strings: They enable easier formatting for multi-line strings, making your code less cluttered.

Conclusion

Adding classes conditionally in JavaScript templates is a straightforward task once you understand the correct syntax. Whether you choose to use string concatenation or template literals, the key is to ensure that you construct the string with the correct structure and evaluate the conditions as needed.

By following the methods outlined in this blog, you'll be able to dynamically manipulate the classes on your elements effectively, improving both aesthetics and functionality in your web projects.

Make sure to try out both approaches and see which one fits best for your specific needs!