How to Call a JavaScript Function from an External JS File in HTML
This guide will walk you through the process of calling a JavaScript function defined in an external file within your HTML document.
1. Create Your External JavaScript File (external.js)
Begin by creating a new JavaScript file (e.g., external.js) and define your function within it:
// external.js
function myFunction() {
alert("This function is called from an external file!");
}
2. Link the External File in Your HTML
Next, include the external JavaScript file within your HTML document using the <script> tag. Make sure you place the script tag either before the closing </body> tag or in the <head> section:
Calling External Functions
3. Call the Function from HTML
Finally, you can call the myFunction from your HTML using the onclick event handler attached to an element (in this case, a button):
When you click the button, the JavaScript function myFunction from the external file will be executed, and you will see the alert message.
Key Points to Remember
- Order Matters: Ensure the
<script>tag linking your external file appears after the element where you want to call the function. This ensures that the function is defined before being called. - Script Placement: You can place your external JavaScript file link within the
<head>or before the closing</body>tag. Both locations are valid, and the choice often depends on your project's structure and preferences. - File Path: The
srcattribute in the<script>tag should point to the correct path of your external JavaScript file relative to the location of your HTML file.
This method allows you to separate your JavaScript code from your HTML, making your code more organized and reusable. You can now easily use functions defined in external.js in different HTML files without repeating the code.