easily parse the return of hrtime
method from process
module into second/milisecond/microsecond/namisecond
var hrtime = require('process.hrtime');
var start = hrtime();
setTimeout(function () {
console.log(hrtime(start));
console.log(hrtime(start, 's') + ' s'); // 0.2s
console.log(hrtime(start, 'ms') + ' ms'); // 200ms
console.log(hrtime(start, 'us') + ' us'); // 200000 us
console.log(hrtime(start, 'ns') + ' ns'); // 200000000 ns
}, 200);