How To Use Css In Javascript

When developing web applications, you might encounter situations where you need to manipulate the styles of elements dynamically. This is where the power of JavaScript comes handy! JavaScript allows you to interact with CSS and modify styles on-the-fly. In this blog post, we will explore different methods to use CSS in JavaScript.

1. Changing Styles with JavaScript

JavaScript allows you to access and manipulate the style properties of an HTML element using the style object. The syntax to change a style property is as follows: = "value";

For example, if you want to change the color and font size of a paragraph element with the id “myParagraph”, you can do so in the following way:

  var myParagraph = document.getElementById("myParagraph"); = "red"; = "24px";

2. Adding and Removing CSS Classes

Another approach to using CSS in JavaScript is by adding or removing CSS classes to HTML elements. First, you need to define the styles in your CSS file or within a <style> tag:

  .highlight {
    background-color: yellow;
    font-weight: bold;  

Now, you can add the ‘highlight’ class to an element using the classList.add() method:

  var myElement = document.getElementById("myElement");

To remove the class, use the classList.remove() method:


You can also toggle a class on and off using the classList.toggle() method:


3. Modifying CSS with JavaScript Libraries

There are several JavaScript libraries, such as jQuery, that provide an easy-to-use API for modifying CSS. In the case of jQuery, you can use the .css() method to get or set the style properties of an element:

  // Get the current font size of an element
  var fontSize = $("#myElement").css("font-size");

  // Set the color and font size of an element
  $("#myElement").css({ "color": "red", "font-size": "24px" });

jQuery also offers methods for adding and removing classes, such as .addClass(), .removeClass(), and .toggleClass().


As you can see, there are multiple ways to use CSS in JavaScript. You can directly manipulate style properties, add or remove classes, or even use libraries like jQuery. The method you choose depends on your requirements and preferences. No matter which approach you take, you now have the power to create dynamic web applications with ease!