How to include JavaScript file into another

To include a JavaScript file into another, you can use the HTML <script> tag. This allows you to reuse code from one file in multiple parts of your project. Here's a more detailed explanation with examples:

Example of Including JavaScript File

Let's say you have two JavaScript files: main.js and helper.js. You want to include the code from helper.js into main.js.

// This is the content of helper.js function showMessage(message) { alert(message); }
// This is the content of main.js showMessage("Hello from main.js using helper.js!");

Including JavaScript File

In your HTML file, you include the JavaScript files using the <script> tag. Make sure to include the helper.js file before the main.js file since the code in main.js relies on the functions defined in helper.js.

<!DOCTYPE html> <html> <head> <title>JavaScript Include Example</title> <script src="helper.js"></script> <script src="main.js"></script> </head> <body> </body> </html>

When the HTML page is loaded, it first loads the helper.js file, which defines the showMessage function. Then, it loads the main.js file, which uses the showMessage function to display an alert.

JavaScript file into another

This way, you've included the code from the helper.js file into the main.js file, allowing you to reuse the function across different parts of your project.

Keep in mind that the order of inclusion matters. Scripts are executed in the order they are loaded. If main.js relies on functions or variables from helper.js, ensure that helper.js is included before main.js.


To include a JavaScript file within another, utilize the HTML <script> tag. By specifying the external file's source using the src attribute, you can integrate its functionality into the main script. This enables reusability and code organization, where the order of inclusion is essential when dependencies exist.