Stream/"read line by line" ajax

Stream/"read line by line" ajax

Is there any way to read a file line by line or by chucks of data with a certain size. Essentially I need to finish requests when they encounter a certain string ("</title>" to be exact) for a browser extension I am developing, to minimise the overload caused by the extension. I believe the idea to be fairly straightforward and in php it would have been as simple as writing a "hello world" script, but in javascript/jquery it seems to be altogether impossible. :/
Thanks in advance for any help,
David Mulder