What is a Web Worker in HTML5?

A web worker is a JavaScript running in the background, without affecting the performance of the page.

Do you have similar website/ Product?

Show in this page just for only $2 (for a month)

Create an Ad

0/60

0/180

Image

Title

Why people should visit you

When executing scripts in an HTML page, the page becomes unresponsive until the script is finished. A web worker is a JavaScript that runs in the background, independently of other scripts, without affecting the performance of the page. You can continue to do whatever you want: clicking, selecting things, etc., while the web worker runs in the background.

Check Web Worker Support Before creating a web worker.

if (typeof(Worker) !== "undefined")
{ // Web worker supported
}
else
{
// Web Worker not supporting.
}

Create a Web Worker File in an external JavaScript.

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.

To create a Web Worker Object The following lines checks if the worker already exists:

if (typeof(w) == "undefined")
{
w = new Worker("demo_workers.js");
}

Add an "onmessage" event listener to the web worker.

w.onmessage = function(event){
document.getElementById("result").innerHTML = event.data;
};

o terminate a web worker, and free browser/computer resources the terminate() method is used.

w.terminate();

After termination reuse the code:

w = undefined;

Web Worker

HTML5

Ayesha

Tech writer at newsandstory