A Simple Button Click Function Call

Step 1. Put a function anywhere between the HEAD tags of your web page:

<script type="text/javascript">
  <!–
    function helloWorld() {
      alert(‘Hello World!’) ;
    }
  // –>
  </script>

Step 2. Somewhere between the BODY tags, make a button that calls the above function.

<input type="button" id="hello-world2" value="Hello" onClick="helloWorld();" />