Jquery custom string comparison function with output percentage

I am looking to write a function in Jquery that compares two 开发者_高级运维strings and returns a percentage of similarity..exactly like the PHP function similar_text:

http://www.php.net/manual/en/function.similar-text.php

Ideas on how to tackle this with Jquery/Javascript? Thanks!

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PHP.JS have it: http://phpjs.org/functions/similar_text:902