How To Call JavaScript Function in HTML: Different Methods 2023

JavaScript functions can be called from an HTML file in several ways. The most common ways to call a JavaScript function from an HTML file are by using an HTML button, a hyperlink, or an event handler.

In this article, we will explore the different methods to call JavaScript functions in HTML file and provide examples of how they can be used.

Ways to Call JavaScript Function in HTML

1. Using an HTML button

One of the most common ways to call a JavaScript function from an HTML file is by using an HTML button. The onclick event of the button can be used to call the function.

<button onclick="myFunction()">Click me</button> <script> function myFunction() { alert("Button was clicked!"); } </script>

2. Using a Hyperlink:

Another way to call a JavaScript function from an HTML file is by using a hyperlink. The href attribute can be set to javascript:functionName() to call the function when the link is clicked.

<a href="javascript:myFunction()">Click me</a> <script> function myFunction() { alert("Link was clicked!"); } </script>

3. Using an Event Handler

An event handler can also be used to call a JavaScript function from an HTML file. The event handler is added to the HTML element, and the function is called when the event occurs.

<div onmouseover="myFunction()">Hover over me</div> <script> function myFunction() { alert("Div was hovered over!"); } </script>

4. Using JavaScript DOM:

You can also call a function from javascript DOM, getElementById . this method is widely used, it finds an element by its id attribute, and after that you can call the function on the element.

<button id="myBtn">Click me</button> <script> var btn = document.getElementById("myBtn"); btn.onclick = function() { alert("Button was clicked!"); } </script>

5. Using addEventListener:

You can also use addEventListener method of DOM to call javascript function from HTML.

<button id="myBtn">Click me</button> <script> var btn = document.getElementById("myBtn"); btn.addEventListener("click", myFunction); function myFunction() { alert("Button was clicked!");

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FAQs:

Can I pass parameters to the JavaScript function when calling it from HTML?

Yes, you can pass parameters to the JavaScript function when calling it from HTML. For example, you can use the following syntax to pass a parameter to a function when calling it from an HTML button:

<button onclick="myFunction('Hello')">Click me</button> <script> function myFunction(param) { alert(param); } </script>

Is it better to put the script at the top or bottom of the HTML file?

It’s generally recommended to put the script at the bottom of the HTML file, just before the closing body tag. This is because JavaScript can slow down the loading of the page and by placing the script at the bottom, it ensures that the page will load first and the script will execute after.

Conclusion:

Calling JavaScript functions from an HTML file is a common task in web development. There are several ways to call a JavaScript function from an HTML file, such as using an HTML button, a hyperlink, an event handler, and JavaScript DOM.

Each of these methods has its own advantages and use cases and it’s important to understand them in order to choose the right one for your project.

Understanding how to call JavaScript functions from HTML is an essential skill for JavaScript developers, as it is widely used in many web development scenarios.

It’s also important to consider edge cases such as passing parameters, placement of script and usage of addEventListener.