how to use javascript from html code example

Example 1: how to use javascript in html

<!-- include an external javascript document -->
<script src="myJavaScript.js" charset="utf-8"></script>

<!-- JavaScript inside html element -->
<script>
  console.log("This is JavaScript");
</script>

Example 2: add javascript

function add(param1, param2) {
    return param1 + param2
}