js获取时间戳

1.Date.parse(new Date())
const timestamp = Date.parse(new Date());
console.log(timestamp);
//输出 1591669256000   13位
2.Math.round(new Date())
const timestamp = Math.round(new Date());
console.log(timestamp);  
//输出 1591669961203   13位
3.(new Date()).valueOf()
const timestamp = (new Date()).valueOf();
console.log(timestamp);
//输出 1591670037603   13位
4.new Date().getTime()
const timestamp = new Date().getTime();
console.log(timestamp);
//输出 1591670068833   13位
5.+new Date()
const timestamp = +new Date();
console.log(timestamp);
//输出 1591670099066   13位