如何计算程序执行时间？

<script type="text/javascript">
		var myDate = new Date();
		
        console.time("sort");

	for(var i = 0;i<1000;i++)
	{ 
		console.log(1);
	}
	
        console.timeEnd("sort");//sort: 192.384033203125ms 

		var myDate1 = new Date();

		console.log(myDate1 -myDate);//192ms
</script>