Generate a Hash from string in Javascript

Question

I need to convert strings to some form of hash. Is this possible in JavaScript?

I\'m not utilizing a server-side language so I can\'t do it that way.

Answer 1

I went for a simple concatenation of char codes converted to hex strings. This serves a relatively narrow purpose, namely just needing a hash representation of a SHORT string (e.g. titles, tags) to be exchanged with a server side that for not relevant reasons can't easily implement the accepted hashCode Java port. Obviously no security application here.

String.prototype.hash = function() {
  var self = this, range = Array(this.length);
  for(var i = 0; i < this.length; i++) {
    range[i] = i;
  }
  return Array.prototype.map.call(range, function(i) {
    return self.charCodeAt(i).toString(16);
  }).join('');
}

This can be made more terse and browser-tolerant with Underscore. Example:

"Lorem Ipsum".hash()
"4c6f72656d20497073756d"

I suppose if you wanted to hash larger strings in similar fashion you could just reduce the char codes and hexify the resulting sum rather than concatenate the individual characters together:

String.prototype.hashLarge = function() {
  var self = this, range = Array(this.length);
  for(var i = 0; i < this.length; i++) {
    range[i] = i;
  }
  return Array.prototype.reduce.call(range, function(sum, i) {
    return sum + self.charCodeAt(i);
  }, 0).toString(16);
}

'One time, I hired a monkey to take notes for me in class. I would just sit back with my mind completely blank while the monkey scribbled on little pieces of paper. At the end of the week, the teacher said, "Class, I want you to write a paper using your notes." So I wrote a paper that said, "Hello! My name is Bingo! I like to climb on things! Can I have a banana? Eek, eek!" I got an F. When I told my mom about it, she said, "I told you, never trust a monkey!"'.hashLarge()
"9ce7"

Naturally more risk of collision with this method, though you could fiddle with the arithmetic in the reduce however you wanted to diversify and lengthen the hash.