When copying automatically add URL

I have seen on few websites that when you copy some text from there, and paste anywhere, it will add the URL of the page from wher开发者_运维知识库e I copied the text.

For example:

This is text I copied.

and when I paste, I get:

This is text I copied.
Read more: http://example.com/abc/def

I'm just curious to know how this is done? How to add additional text in the copied text?

Example: Check this question (or any other) on answers.com. Copy the question text and paste. Tested with Firefox latest version.

There are many online tools which provide this and other website/blog management utilities. Answer.com is also using one such service named tynt. Open the link, scroll down to the bottom and you can see answer.com in featured clients ;). For more information.

Zeroclipboard should help you modify the clipboard content. It's a flash movie that is hidden in the browser and exposes a JavaScript API to access the clipboard.

Example.

var clip = new ZeroClipboard.Client();
clip.addEventListener('complete', function(client, text) {
    clip.setText(text + "Read more at www.");
});