JS: Timing JavaScript Code

To test speed of 2 JavaScript code, you just get a time stamp. Like this:

// the function to test
function range (n) {
    const arr = Array(n);
    for (let idx = 0; idx <= n; idx++) {
        arr[idx] = idx;
    };
    return arr;
}

// timing
const test_repeat_count = 50;
const start = new Date().getTime();
for (let i = 0; i < test_repeat_count; ++i) {
    range(9999);
}
const end = new Date().getTime();

// result
console.log( end - start);