Binary Search

gistfile1.js

function bSearch(items, value){
	
	var startIndex = 0;
	var stopIndex = items.length-1;
	var middle = Math.floor((startIndex + stopIndex)/2);

	while(value !== items[middle] && startIndex < stopIndex){
		if(value > items[middle]){
			startIndex = middle + 1;
		}else if(value < items[middle]){
			stopIndex=middle-1;
		}

		middle = Math.floor(( startIndex + stopIndex ) / 2);

	}

	return (items[middle] === value) ? middle : -1;

};

var items = [1, 3, 7, 9, 23, 34, 45, 52, 65, 67, 76, 82, 84, 86, 92, 100, 104, 121];

console.log("34 is at index: ", bSearch(items, 34));