Mersenne Twister

mersenne.js

var MersenneTwister = function(seed) {
    // Holds the state of the register
    this.state = [seed];
    this.index = 0;
    
    for(var i=1;i<=623;i++) {
        var s = this.state[i-1] ^ (this.state[i-1] >>> 30);
        this.state[i] = (((((s & 0xffff0000) >>> 16) * 1812433253) << 16) + (s & 0x0000ffff) * 1812433253) + i;
        this.state[i] >>>= 0;
    }
    
    // Extract a tempered pseudorandom number based on the index-th value,
    // calling generate_numbers() every 624 numbers
    this.random = function() {
        if(this.index == 0) this.generate_numbers();
        
        var y = this.state[this.index];
        y = y ^ (y >>> 11);
        y = y ^ ((y << 7) & 0x9d2c5680);
        y = y ^ ((y << 15) & 0xefc60000);
        y = y ^ (y >>> 18);
        
        this.index = (this.index + 1) % 624;
        return (y >>> 0) / 4294967296;
    }
    
    // Generate an array of 624 untempered numbers
    this.generate_numbers = function() {
        for(var i=0;i<623;i++) {
            var y = ((this.state[i] >>> 32) & 1) + ((this.state[(i+1) % 624]) & (1<<31));
            this.state[i] = this.state[(i + 397) % 624] ^ (y >>> 1);
            if(y % 2 != 0) this.state[i] = this.state[i] ^ 2567483615;
        }
    }
};
                  
var mt = new MersenneTwister(150);
alert(mt.random());
alert(mt.random());