时间戳的转换

（一）时间戳转为当前时间

	var a = 1594810549
	
	console.log(timestampToTime(a)) //2020-07-15->18:55:49

	function timestampToTime(timestamp){
		var date = new Date(timestamp * 1000);//时间戳为10位需*1000，时间戳为13位的话不需乘1000
		Y = date.getFullYear() + '-';
		M = (date.getMonth()+1 < 10 ? '0'+(date.getMonth()+1) : date.getMonth()+1) + '-';
		D = date.getDate() < 10 ? '0'+(date.getDate()) : date.getDate();
		h = date.getHours() + ':';
		m = date.getMinutes() + ':';
		s = date.getSeconds();
		return Y+M+D+ '->' +h+m+s;
	}

　　

（二）当前时间转为时间戳

	var date = new Date('2020-7-15 18:55:49:123');//后三位为毫秒
	    var time1 = date.getTime();
	    var time2 = date.valueOf();
	    var time3 = Date.parse(date);
	    console.log(time1);//1594810549123
	    console.log(time2);//1594810549123
	    console.log(time3);//1594810549000
		

　附带一个for in 小循环

	var b = [1,2,3,4]
	for(let index in b){
		console.log(b[index])
	}