Use lastIndexOf as a faster means of checking "starts with", put quickes...

...t comparison first

lastIndexOf(string, 0) is actually quite a bit faster than indexOf(string) for long strings when there's no match.

Details:
http://jsperf.com/js-startswith/8

Since accessing a hard-coded value should be slightly faster than the lookups to length, put the check for iForce first.