By Vishal Basumatary in javascript — Mar 24, 2023

difference between styling app.js and index

Difference between styling app.js and index.html

When it comes to styling web applications, there are two main ways to do it - by writing CSS code in a separate file and linking it to the HTML file, or by using JavaScript to manipulate the CSS styles directly. In the context of React applications, where we use JSX syntax and create components, the two main files we work with are usually "app.js" and "index.html".

Styling with CSS

The most common way to style web applications is by writing CSS code in a separate file and linking it to the HTML file. This is usually done in the "index.html" file, where we add a link to our CSS file in the head section:

<head>
  <link rel="stylesheet" href="styles.css">
</head>

Then we can write our CSS code in the "styles.css" file and use selectors to target specific HTML elements and apply styles to them. For example:

body {
  background-color: #f5f5f5;
}

h1 {
  font-size: 2rem;
  color: #333;
}

This will set the background color of the body element to light gray and change the font size and color of all h1 elements.

Styling with JavaScript

Another way to style web applications is by using JavaScript to manipulate the CSS styles directly. This can be done in the "app.js" file, where we can access the DOM elements and modify their styles using the style property:

const myHeading = document.querySelector('h1');
myHeading.style.fontSize = '2rem';
myHeading.style.color = '#333';

This will select the first h1 element on the page and set its font size and color to the values specified.

While both methods can achieve the same result, there are some differences to consider. Using CSS allows us to separate our styling from our logic, making it easier to maintain and reuse styles across multiple pages. On the other hand, using JavaScript can be more flexible in certain situations, such as when we need to dynamically change styles based on user input or other events.

Ultimately, the choice between CSS and JavaScript for styling will depend on the specific needs of your application and your personal preferences as a developer.