index.html

<!DOCTYPEhtml><html><body><p>Countnumbers:<outputid="result"></output></p><buttononclick="startWorker()">StartWorker</button><buttononclick="stopWorker()">StopWorker</button><br/><br/><script>varw=null;functionstartWorker(){if(typeof(Worker)!=="undefined"){if(w==null){w=newWorker("worker.js");}w.onmessage=function(event){document.getElementById("result").innerHTML=event.data;};}else{document.getElementById("result").innerHTML="Sorry,yourbrowserdoesnotsupportWebWorkers...";}}functionstopWorker(){if(w==null){return;}w.terminate();w=null;}</script></body></html>

worker.js

vari=0;functiontimedCount(){i=i+1;postMessage(i);setTimeout("timedCount()",500);}timedCount();