Web Workers: Create a Web Worker File

//Here, we create a script that counts
//The script is stored in the "demo_workers.js" file

var i = 0;

function timedCount() {
  i = i + 1;
  postMessage(i);
  setTimeout("timedCount()",500);
}

timedCount();

The important part of the code above is the postMessage() method - which is used to post a message back to the HTML page.

Normally web workers are not used for such simple scripts, but for more CPU intensive tasks.