binary_search.js

// бинарный поиск

var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

function binary_search(num) {
	var low = 0;
	var high = arr.length - 1;

	while (low <= high) {
		var middleIndex = Math.round((low + high) / 2);

		if (arr[middleIndex] === num) {
			return console.log(`Num ${num} — index: ${middleIndex}`);
		} else if (arr[middleIndex] > num) {
			high = middleIndex - 1;
		} else {
			low = middleIndex + 1;
		}
	}

	return console.log(`Num ${num} — none!`);
}

binary_search(20);
binary_search(8);