Implement binary search. Given an array and a number to look for, return the index of the element in the array.
function binarySearch(numbers, element) {
}
const chai = require("chai");
const assert = chai.assert;
describe("Solution", function() {
it("return index of searching element", function() {
assert.strictEqual(binarySearch([1, 2, 3, 4, 5, 6, 7], 4), 3);
assert.strictEqual(binarySearch([1, 2, 3, 4, 5, 6, 7], 2), 1);
assert.strictEqual(binarySearch([1, 2, 3, 4, 5, 6, 7], 8), -1);
});
});