simple stopwatch in JavaScript 1.8

stopwatch.js

// for Firefox 31
const time = (process, n=1) =>
{
    let total = 0.0;
    
    for (let i = 0; i < n; ++i)
    {
        const start = window.performance.now();
        process();
        const elapsed = window.performance.now() - start;
        total += elapsed / n;
    }

    console.log(total);
};


// how to use

const fib = (i, n = i) => i > 0 ? fib(i - 1, n + i - 1) : n;

time(_=> fib(6000) );