js时间格式化

照抄element-ui的时间格式化，将当前时间或者自定义时间格式化为自己需要的格式

dateFormat.js 代码

 function pad(val, len) {
     val = String(val);
     len = len || 2;
     while (val.length < len) {
         val = '0' + val;
     }
     return val;
 }
 var formatFlags = {
     D: function (dateObj) {
         return dateObj.getDay();
     },
     DD: function (dateObj) {
         return pad(dateObj.getDay());
     },
     d: function (dateObj) {
         return dateObj.getDate();
     },
     dd: function (dateObj) {
         return pad(dateObj.getDate());
     },
     M: function (dateObj) {
         return dateObj.getMonth() + 1;
     },
     MM: function (dateObj) {
         return pad(dateObj.getMonth() + 1);
     },
     yy: function (dateObj) {
         return pad(String(dateObj.getFullYear()), 4).substr(2);
     },
     yyyy: function (dateObj) {
         return pad(dateObj.getFullYear(), 4);
     },
     h: function (dateObj) {
         return dateObj.getHours() % 12 || 12;
     },
     hh: function (dateObj) {
         return pad(dateObj.getHours() % 12 || 12);
     },
     H: function (dateObj) {
         return dateObj.getHours();
     },
     HH: function (dateObj) {
         return pad(dateObj.getHours());
     },
     m: function (dateObj) {
         return dateObj.getMinutes();
     },
     mm: function (dateObj) {
         return pad(dateObj.getMinutes());
     },
     s: function (dateObj) {
         return dateObj.getSeconds();
     },
     ss: function (dateObj) {
         return pad(dateObj.getSeconds());
     },
     S: function (dateObj) {
         return Math.round(dateObj.getMilliseconds() / 100);
     },
     SS: function (dateObj) {
         return pad(Math.round(dateObj.getMilliseconds() / 10), 2);
     },
 };
 var token = /d{1,4}|M{1,4}|yy(?:yy)?|S{1,3}|Do|ZZ|([HhMsDm])\1?|[aA]|"[^"]*"|'[^']*'/g;
 var literal = /\[([^]*?)\]/gm;

 function format(dateObj, mask = 'yyyy-MM-dd') {
     if (!dateObj) {
         dateObj = new Date();
     }
     if (Object.prototype.toString.call(dateObj) !== '[object Date]' || isNaN(dateObj.getTime())) {
       dateObj = new Date();
     }

     var literals = [];
     mask = mask.replace(literal, function ($0, $1) {
         literals.push($1);
         return '@@@';
     });

     mask = mask.replace(token, function ($0) {
         return $0 in formatFlags ? formatFlags[$0](dateObj) : $0.slice(1, $0.length - 1);
     });

     return mask.replace(/@@@/g, function () {
         return literals.shift();
     });
 }
 //给当前时间格式化
 function currentDateFormat(mask) {
   return format(new Date(), mask);
 }
 //给自定义时间格式化
 function customDateFormat(datestr, mask) {
     let dateObj = null;
     if (!datestr) {
         dateObj = new Date();
     } else {
         dateObj = new Date(datestr);
     }
    return format(dateObj, mask);
 }
 export {
     currentDateFormat,
     customDateFormat,
 };

方法

import { currentDateFormat, customDateFormat } from "@/util/dateFormat.js";

• currentDateFormat 对当前时间进行格式化
  • 格式化格式，默认'yyyy-MM-dd'，最全格式为 'yyyy-MM-dd HH:mm:ss'
• customDateFormat 对自自定义时间进行格式化
  • 想要转换的日期字符串，例如'2020-10-01 08:30:00'
  • 格式化格式，默认'yyyy-MM-dd'，最全格式为 'yyyy-MM-dd HH:mm:ss'

例子

//currentDateFormat
currentDateFormat(); //2021-04-07
currentDateFormat("yyyy-MM-dd HH:mm:ss"); //2021-04-07 10:03:23
currentDateFormat("yyyy-MM-dd HH:mm"); //2021-04-07 10:03
currentDateFormat("yyyy-MM-dd HH"); //2021-04-07 10
currentDateFormat("yyyy-MM-dd"); //2021-04-07
currentDateFormat("yyyy-MM"); //2021-04
currentDateFormat("yyyy"); //2021
currentDateFormat("MM-dd"); //04-07
currentDateFormat("MM"); //04
currentDateFormat("dd"); //07
currentDateFormat("HH:mm:ss"); //10:03:23
currentDateFormat("HH:mm"); //10:03
currentDateFormat("HH"); //10
currentDateFormat("mm:ss"); //03:23
currentDateFormat("mm:ss"); //03:23
//customDateFormat
customDateFormat(); // 2021-04-07
customDateFormat("2010-10-18 19:17:54"); //2010-10-18
customDateFormat("2010-10-18 19:17:54", "yyyy-MM"); //2010-10
customDateFormat("2010-10-18 19:17:54", "MM-dd"); //10-18
customDateFormat("2010-10-18 19:17:54", "MM"); //10
customDateFormat("2010-10-18 19:17:54", "dd"); //18
customDateFormat("2010-10-18 19:17:54", "HH:mm:ss"); //19:17:54
customDateFormat("aaaaaa", "HH:mm:ss"); //10:55:08