js: maximum sub array in linear time

submax.js

// O(n)
Array.prototype.submax = function() {
	var max = sum = 0;
	for(var i = 0, l = this.length; i < l; i++) {
		sum = Math.max(sum + this[i], 0);
		max = Math.max(max, sum);
	}
	return max;
}

var max = sum = 0; should be var max = 0, sum = 0;. Otherwise, sum will be global.