stripe/jquery.payment — pull request #34 by akre54 (2013-02-18 06:33:14+00:00)
Title: use isNaN and parseInt for fasterness

Using `isNaN(parseInt(digit, 10))` is faster than `unless /^\d+$/.test(digit)` (see [jsperf](http://jsperf.com/test-if-number-2)), and I think reads a little cleaner. The unary operator (`+digit`) is essentially a shorthand for `Number(digit)`, which looks even cleaner but is slightly slower.