Compare 2 strings and display difference (php or javascript)

Comparing must work on-the-fly, so this must be done via javascript or with php (will make javascript ajax request).

What I need is probably advanced difference showing, so it will be probably best if there is any kind of good supported library.

This picture shows exactly what I need >

Added #1: I found this http://ejohn.org/projects/javascript-diff-algorithm/ (example http://www.djsipe.com/js-diff/) which is ok, but doesn't support multi开发者_开发知识库line? and it changes the whole word when only one character is different...

Added #2: I tested php script ( https://github.com/paulgb/simplediff/ ) but it has flaws.

Added #3: I found what i was looking for ( http://code.google.com/p/google-diff-match-patch/ )

This answer to a related question seems promising for javascript. google-diff-match-patch

It provides an API which will take care of all the complex and well known algorithms. However you'll have to do some work with the presentation.

PHP is more versatile there is a lot of diff tools out there. Look this other related question Calculate text diffs in PHP.

See Highlight the difference between two strings in PHP