HTML5 Web Workers / PDF

Sample of the pdf document :

What is a Web Worker?

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.

---

Browser Support

Web workers are supported in all major browsers, except Internet Explorer.

---

HTML5 Web Workers Example

The example below creates a simple web worker that count numbers in the background:

Example

Count numbers:

Start Worker Stop Worker 

---

Check Web Worker Support

Before creating a web worker, check whether the user's browser supports it:

if(typeof(Worker)!=="undefined")
  {
  // Yes! Web worker support!
  // Some code.....
  }
else
  {
  // Sorry! No Web Worker support..
  }

---

Create a Web Worker File

Now, let's create our web worker in an external JavaScript.

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 posts a message back to the H0....

                                                   

Click here for  Download PDF / FREE