Find Collatz Chain Length

gistfile1.js

	var nums = [], lengths = [];
	function findNumLength(n) {
		//preliminary check to see if 
		//we've done this number before
		var indexOf = nums.indexOf(n);
		if(indexOf !== -1) {
			return lengths[indexOf];
		}
		function even (n2) { return n2%2===0; }
		if(n===1) {
			return 1;
		}
		if(even(n)) {
			l = findNumLength(n/2) + 1;
			if(indexOf===-1) { 
				lengths.splice(0,0 ,l);
				nums.push(n);
			}
			return l;
		}
		else {
			l = findNumLength(3*n + 1) + 1;
			if(indexOf===-1){
				lengths.splice(0,0,l);
				nums.push(n);
			}
			return l;
		}
	}