A simple javascript random library.

random.js

(function (root, factory) {
    if (typeof define === 'function' && define.amd) {
        define([], factory);
    } else if (typeof exports === 'object') {
        module.exports = factory();
    } else {
        root['strHash'] = factory();
  }
}(this, function () {

	var Random = {};

	var _rand = Math.random,
		max = Math.max,
		min = Math.min,
		floor = Math.floor,
		ceil = Math.ceil
		round = Math.round;
		
	function type(o){
		return Object.prototype.toString.call(o).slice(8,-1).toLowerCase();
	}

	function isNumber(o){
		return type(o) === 'number';
	}

	var isInt = Number && Number.isInteger ? Number.isInteger : function(n){
		return n >> 0 === n;
	};

	function checkInt(name,val){
		if( !isInt(val) ){
			throw new Error('params ' + (name || '') + 'must be integer.');
		}
		return;
	}


	function checkNum(name,val){
		if( !isNumber(val) ){
			throw new Error('params ' + (name || '') + 'is not a number.');
		}
		return;	
	}

	Random.random = function(start,stop){
		var argNum = arguments.length;
		if( argNum === 1 ){
			stop = start;
			start = 0;
		} else if( argNum === 0 ){
			start = 0;
			stop = 1;
		}

		checkNum('start',start);
		checkNum('stop',stop);

		return start + (stop - start)*_rand();
	}

	Random.randomInt = function(start,stop,step){
		if( !stop ){
			stop = start;
			start = 0;
		}
		step = step || 1;

		checkInt('start',start);
		checkInt('stop',stop);
		checkInt('step',step);

		var n = (stop - start) / step >> 0;

		return start + step * (n * _rand() >> 0);

	}

	Random.choice = function(seq){
		return seq[this.randomInt(seq.length)];
	};

	Random.shuffle = function(seq){
		var rand,
			shuffled = [];
		for( var i = 0, l = seq.length; i < l; i++ ){
			rand = Random.random(i)
			shuffled[i] = shuffled[rand];
			shuffled[rand] = seq[i];
		}

		return shuffled;
	};

	Random.sample = function(population,k){
		return Random.shuffled(population).slice(k);
	};

    return Random;
}));