To call a JavaScript function from an HTML file, you can use the onclick attribute in an HTML element. Here's an example:
html<!DOCTYPE html>
<html>
<head>
<title>Call a function from HTML</title>
<script>
function sayHello() {
alert('Hello, world!');
}
</script>
</head>
<body>
<button onclick="sayHello()">Click me</button>
</body>
</html>
In this example, we defined a JavaScript function named sayHello that displays an alert message with the text "Hello, world!". We then created a button element and used the onclick attribute to call the sayHello function when the button is clicked.
Note that you need to include the JavaScript code in a <script> tag inside the HTML file, either in the <head> or <body> section. Also, make sure that the function name in the onclick attribute matches the name of the function defined in the JavaScript code.