JavaScript in HTML

JavaScript makes pages dynamic. You can use script tag to load and run JS. Loading and Running JS depends on below attribute.

• default - load and run JS immedietly. HTML parsing is paused during loading and running JS.
• async - load JS asynchronously and when the JS is ready to run, pause the HTML parsing and run JS and then resume HTML parsing. HTML parsing is paused only when the JS is being run.
• defer - Load JS asynchronously. But run JS after HTML parsing is done. In this case HTML parsing is never paused.

<script>
alert("This is JS!");
</script>