JavaScript二分查找（折半查找）

function binarySearch(arr, key) {
	var low = 0,
	    high = arr.length - 1;
	while(low <= high) {
		var mid = parseInt((high + low) /  2);
		if(key == arr[mid]) {
			return mid;
		} else if (key > arr[mid]) {
			low = mid + 1;
		} else if(key < arr[mid]) {
			high = mid - 1;
		} else {
			return -1;
		}
	}
}