JS时间戳、日期格式YYYYMMDD和字符串的转换

1. 当前时间转换时间戳

var time1= new Date().getTime();
var time2 = (new Date()).valueOf();
var time3 = Date.parse(new Date());

2. 指定日期转换时间戳

time = '2020-05-08'
const date = new Date(time).getTime()		
//	getTime()返回数值的单位是毫秒

3. 获取指定的日期格式YYYY-MM-DD

const date = new Date(time).getTime()		
var d = new Date(date);
var year = d.getFullYear();
var month = d.getMonth() + 1;
String(month).length < 2 ? (month = '0' + month):month;
//	三目运算符
var day = d.getDate();
String(day).length < 2 ? (day = '0' + day):day;
//	var hour=now.getHours(); 
//	var minute=now.getMinutes(); 
//	var second=now.getSeconds(); 
var datetime = year + "-" + month + "-" + day;
return datetime;