Can You Change CSS Styles Using Js?

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Js, or JavaScript, is a versatile scripting language web developers use. It transforms static, monotonous web pages into a dynamic and interactive platform. JavaScript is majorly used for modifying CSS styles. CSS or Cascading Style Sheets characterize the layout and presentation of web pages. It specifies the formatting of the elements on the page, i.e., their size, color, and position. But, CSS cannot make changes to the styles dynamically.

Change css styles using js

HTML, CSS, and JavaScript are significant layers of front-end development. Integrating CSS and Js can create dynamic webpages with an exceptional front-end user interface. The naming in the case of Js is a bit varied. CSS attribute names with hyphens change into inter-capitalized single words in Js. For instance, the background-color property in CSS changes to backgroundColor in Js. This article discusses different ways user can change CSS styles using Js.


Changing CSS Inline Styles

Before applying changes to the CSS styles of a page, users need to select the elements to modify. There are majorly three ways to select elements in JavaScript. It includes the document.getElementById() method, the document.getElementsByTagName() method, and the document.querySelector() method.

The document.getElementById() method chooses an element with a specific id while the document.getElementsByTagName() method selects all elements with a specified tag name.

The document.querySelector() method allows users to select elements based on CSS selectors. After selection, you can modify the style attribute to change the styles. The below code changes the background color to red.

document.getElementById(“myElement”).style.backgroundColor = “red”;

Inlines styles in css

Kindly note that Js style preference precedes the CSS style if already defined. This method modifies styles one by one. Users can also set multiple styles simultaneously using Js by parsing the string value to cssText as shown below:

document.getElementById(“myElement”).style.cssText = “background-color: red; font-size: 20px; width: 100px;”;

Changing CSS Class

JavaScript can change the class of an element by the className property. For example, the following code changes the class of an element to “newClass“:

document.getElementById(“myElement”).className = “newClass”;

Changing CSS Dynamically

Dynamically changing CSS properties is a must when users encounter a large amount of data that needs modification. By exploiting this property, users can apply changes that are also applicable to future elements. This creates a need to change the CSS sheet as a whole.

Dynamically change css

The user selects the required stylesheet and loops through all its rules to get the desired element. You can then modify it as per requirement.

Appending/Deleting A CSS Sheet

Users can append or replace the CSS sheet by following simple steps. It is useful when we have multiple stylesheets for a dynamic webpage. Create a new stylesheet using template literals. Select the head of the page and append the new stylesheet content using “document.createTextNode” and “appendChild“. 

When “!important” is used in CSS, this overwrites any functionality already written in HTML. To override this, users can use the priority parameter on “setProperty” function of Js.


Multiple JavaScript libraries, such as jQuery and Lodash, provide convenient methods for changing styles. For example, jQuery has the css() method, which allows users to change the styles of an element with a single line of code. This article broadly covers ways to change CSS styles using Js. Developers can always explore further and develop innovative ideas to integrate CSS and Js. 

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