highlightTextarea is a jQuery plugin which allows you to highlight words and sentences into textareas. Words are defined in a jQuery array and you can customize highlight color and case sensitivity. The highlighting updates itself when typing in the textarea and follows scroll and resizing (with jQuery-UI).
added by Wolfgang Reutz, instead of highlighting words, it's possible to highlight ranges of text by character, eg. from 1-10, 21-45 and 105-150. This is useful if you would like to highlight text a user has selected with his / her mouse. By setting a range, the wordslist gets cleared and vice versa by setting a wordlist the rangelist gets cleared.
Full details and documentation can be found on the project page here: