Comparing large strings in JavaScript with a hash

Question

I have a form with a textarea that can contain large amounts of content (say, articles for a blog) edited using one of a number of third party rich text editors. I\'m trying to

Answer 1

I made a JSperf rev that might be useful here for performance measuring. Please add different revisions and different types of checks to the ones I made!

http://jsperf.com/long-string-comparison/2

I found two major results

• When strings are identical performance is murdered; from ~9000000 ops/s to ~250 ops/sec (chrome)

• The 64bit version of IE9 is much slower on my PC, results from the same tests:

  +------------+------------+
  | IE9 64bit  |  IE9 32bit |
  +------------+------------+
  | 4,270,414  | 8,667,472  |
  | 2,270,234  | 8,682,461  |
  +------------+------------+
  

Sadly, jsperf logged both results as simply "IE 9".

Even a precursory look at JS MD5 performance tells me that it is very, very slow (at least for large strings, see http://jsperf.com/md5-shootout/18 - peaks at 70 ops/sec). I would want to go as far as to try AJAXing the hash calculation or the comparison to the backend but I don't have time to test, sorry!