Mastering the Art: How to Change CSS in JS – Simple Guide

how to change css in js

JavaScript is a powerful programming language that allows you to modify HTML and CSS dynamically. In this article, we will explore how to change CSS styles using JavaScript. By the end of this article, you’ll have a clear understanding of how to manipulate CSS properties and styles effectively. Let’s get started!

Key Takeaways:

  • JavaScript is a powerful tool for modifying CSS styles dynamically.
  • With JavaScript, you can update CSS properties and styles in real-time.
  • Techniques for changing CSS styles in JavaScript include inline style manipulation, class manipulation, and libraries like styled-components.
  • Practical examples and code snippets will help you understand how to modify CSS using JavaScript.
  • Optimizing your CSS modifications in JavaScript will result in cleaner and more efficient code.

Understanding JavaScript CSS Manipulation

JavaScript is a powerful tool that can be used to modify CSS styles dynamically and update them in real-time. This ability to manipulate CSS using JavaScript opens up a world of possibilities for web developers.

Whether you are looking to modify text, images, or layout, JavaScript gives you the ability to make changes on-the-fly. With its ability to respond to user interactions and real-time data, dynamic CSS modification with JavaScript can create a more engaging and interactive user experience.

Modifying CSS using JavaScript involves updating the properties of CSS elements through JavaScript code. You can change properties in multiple ways, including:

  • Using .style property to modify inline styles
  • Using .classList property to change class attributes
  • Using libraries like styled-components to manipulate CSS styles

By using these techniques, you can easily update your website’s appearance based on user input or dynamic data.

Dynamic CSS modification with JavaScript requires a solid understanding of both CSS and JavaScript. By incorporating the concepts and techniques discussed in this article, you can develop your skills in modifying CSS using JavaScript and create dynamic and visually appealing websites or web applications.

Techniques for Changing CSS in JS

Once you understand the concept of JavaScript CSS manipulation, you can start exploring various techniques for changing CSS styles in JavaScript. Manipulating CSS through JavaScript can be achieved through inline style manipulation, class manipulation, and using libraries like styled-components.

Inline Style Manipulation

One of the simplest ways to alter CSS properties in JavaScript is by directly manipulating the style property of an HTML element. Here’s an example:


<div id=”myDiv”>Hello World!</div>

// JavaScript

const myDiv = document.getElementById(“myDiv”); = “red”;

The above code changes the text color of a div element with the ID “myDiv” to red by setting the style.color property to “red”.

Class Manipulation

Another technique for manipulating CSS styles in JavaScript is through class manipulation. This involves adding, removing, or toggling classes on HTML elements to apply predefined styles. Here’s an example:


<div id=”myDiv” class=”default”>Hello World!</div>

// CSS

.default {

 background-color: yellow;


.highlighted {

 background-color: red;


// JavaScript

const myDiv = document.getElementById(“myDiv”);


The above code adds the “highlighted” class to a div element with the ID “myDiv”, changing its background color to red as defined in the CSS style of the “highlighted” class.

Using Libraries like Styled-components

Finally, one of the most popular ways to manipulate CSS styles in JavaScript is through using libraries like styled-components. These libraries allow you to define styles directly in your JavaScript code as if they were CSS stylesheets. Here’s an example:

// JavaScript with styled-components

import styled from ‘styled-components’;

const Button = styled.button`

 background-color: ${props => props.primary ? “blue” : “white”};

 color: ${props => props.primary ? “white” : “blue”};


// Usage in React component

<Button primary>Click me</Button>

The above code defines a styled button component that changes its background and text color depending on the value of the “primary” prop passed to it. This technique provides a clean and easily maintainable way of manipulating CSS styles in JavaScript code.

By mastering these techniques, you can confidently alter CSS properties using JavaScript and manipulate CSS styles effectively, giving you greater control over the appearance of your websites or web applications.

Examples and Code Snippets for CSS Modification with JS

Let’s dive into some practical examples of how to adjust CSS through JavaScript. These examples will demonstrate how to dynamically modify CSS styles and properties to enhance the appearance and functionality of your website or web application.

Example 1: Inline Style Manipulation

One of the simplest methods for changing CSS styles in JavaScript is through inline style manipulation. Here’s an example:

//Get the element to be modified
const element = document.getElementById(“myElement”);
//Change the background color = “blue”;

In this example, we select an element with the ID of “myElement” and modify its background color to blue. It’s that simple!

Example 2: Class Manipulation

The second method we will explore is class manipulation. This method allows you to change the CSS styles of an element by adding, removing, or toggling classes. Here’s an example:

//Get the element to be modified
const element = document.getElementById(“myElement”);
//Add a class to modify the element’s styles

In this example, we select the element with the ID of “myElement” and add the class “myClass” to it. This class would contain CSS styles to modify the element’s appearance.

Example 3: Using Libraries like styled-components

Another popular method for changing CSS styles in JavaScript is using libraries like styled-components. This method allows you to write CSS styles in JavaScript, making it easier to manage and modify styles dynamically. Here’s an example:

//Define a styled component
const Button = styled.button`
background-color: blue;
color: white;

In this example, we define a styled component called “Button” that has a blue background color and white text color. We can then use this component wherever we need a button element with this styling.

These examples demonstrate just a few of the many techniques for adjusting CSS through JavaScript. By using these methods and experimenting with others, you can create dynamic and visually appealing websites and web applications.

Tips for Optimal CSS Modification in JS

Modifying CSS styles using JavaScript has its challenges. To ensure optimal performance and maintainability of your codebase, it is essential to follow best practices. Here are some valuable tips for effectively changing CSS styles using JavaScript:

  • Minimize the use of inline styles: Although it is tempting to use inline styles for quick CSS modifications, it is generally not recommended. Inline styles can affect code readability and make maintenance more challenging, especially for larger codebases. Instead, try to use class manipulation and external stylesheets as much as possible.
  • Use descriptive class names: When creating class names, use descriptive names that reflect the purpose of the class. This makes it easier to understand and maintain the codebase. Avoid using vague or generic class names like “box” or “container.”
  • Keep CSS styles separate from JavaScript: Avoid mixing JavaScript and CSS codes in the same file. Separating the two makes it easier to find and modify specific sections of the codebase. Moreover, separating CSS styles from JavaScript helps maintain a clean and organized codebase.
  • Use CSS preprocessors: CSS preprocessors such as Sass or Less can help optimize and simplify CSS stylesheets. CSS preprocessors allow you to use variables, functions, and other programming constructs, making CSS modifications more efficient and less prone to errors.
  • Optimize for performance: When modifying CSS styles using JavaScript, it is important to optimize for performance. Optimize the code by caching selectors, avoiding unnecessary DOM manipulations, and minimizing the use of heavy CSS animations or transitions.

By following these tips, you can ensure that your CSS modifications using JavaScript are effective, maintainable, and optimized for performance.

Tips for Optimal CSS Modification in JS

When it comes to changing CSS styles using JavaScript, there are a few tips and techniques you can use to optimize your code and ensure it is efficient and easy to maintain.

1. Use Specificity

When selecting elements to modify, use specificity to ensure you are targeting the correct elements and properties. This can help prevent unintended changes to other elements on the page and make your code more efficient.

2. Minimize DOM Manipulation

DOM manipulation can be expensive in terms of performance, so try to minimize it whenever possible. Instead, consider using CSS classes or libraries like styled-components to update styles.

3. Cache Your Selectors

If you are repeatedly selecting the same element or group of elements, consider caching your selectors to avoid redundant DOM traversals and improve performance.

4. Use Vendor Prefixes

When modifying CSS properties, use vendor prefixes to ensure compatibility across different browsers. This can help prevent unexpected behavior or layout issues on certain devices or browsers.

5. Optimize for Readability

Finally, optimize your code for readability and maintainability. This can include using comments, formatting your code consistently, and using descriptive variable and function names.

By following these tips, you can ensure that your code for changing CSS styles using JavaScript is clean, efficient, and optimized for performance.


Q: What is JavaScript CSS manipulation?

A: JavaScript CSS manipulation refers to the technique of using JavaScript to modify CSS styles dynamically. It allows developers to update CSS properties in real-time and create dynamic and visually appealing websites or web applications.

Q: How can I change CSS styles using JavaScript?

A: There are various techniques for changing CSS styles in JavaScript. You can manipulate inline styles, manipulate classes, or use libraries like styled-components. These methods allow you to alter CSS properties and customize the appearance of your web elements.

Q: Why should I change CSS using JavaScript?

A: Changing CSS using JavaScript provides flexibility and enables dynamic updates to your website or web application. It allows for interactive user experiences, responsive design, and the ability to adjust styles based on user actions or other dynamic factors.

Q: Are there any best practices for CSS modification in JS?

A: Yes, optimizing CSS modification in JavaScript involves writing clean and efficient code. It is recommended to separate CSS and JavaScript logic, utilize CSS classes for styling, and leverage the power of CSS preprocessors when necessary.

Q: Can you provide examples of CSS modification with JS?

A: Certainly! Here are a few code snippets that demonstrate how to change CSS using JavaScript:

// Manipulating inline styles = "red";

// Manipulating classes

// Using styled-components library
const StyledButton = styled.button`
  background-color: ${props => props.primary ? "blue" : "gray"};

Q: How do I ensure optimal performance when changing CSS with JS?

A: To optimize CSS modification with JavaScript, it is important to minimize unnecessary style recalculations, avoid excessive use of inline styles, and leverage CSS animation and transition properties for smooth transitions.

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