Playing with hashing algorithms

Hasher.js

// use a hashing algorithm (in this case, SHA-1) to predictably assign
// a key to a particular slot. May be useful for sharding purposes.
// Based off of ideas found at:
//
// https://github.com/antirez/redis/blob/master/design-documents/REDIS-CLUSTER

var crypto = require('crypto');

// digits -- number of digits to check
// slotSize -- number of slots to assign to
var Hasher = function(digits, slotSize) {
	var maxDigitsSize = Math.pow(16, digits);
	
	if(slotSize > maxDigitsSize) {
		throw("slotSize must be < 16 ^ " + digits);
	}
	this.hash = function(key) {
		var h = crypto.createHash('sha1').update(key).digest("hex");
		var significants = h.substring(h.length - digits);
		var decimalSignificants = parseInt(significants, 16);
		
		return Math.floor(
			slotSize * (decimalSignificants / maxDigitsSize)
		);
	}
}
//var hasher = new Hasher(10, 1024);
//
// console.log(hasher.hash("h")); // => 423
// console.log(hasher.hash("h")); // => 423
// console.log(hasher.hash("hello, world!")); // => 667
// console.log(hasher.hash("hello, world"));  // => 456