Method of js time formatting and conversion

Recently, when practicing or writing projects, I often encounter the problem of time format conversion. Today I will summarize it.

1. Convert the date to the specified format ( yyyy-MM-dd hh:mm:ss and other formats)

Encapsulation method format

//date指的是new Date(),fmt是格式化的格式
 format=(date,fmt)=>{
    
    
    var o = {
    
     
        "M+" : date.getMonth()+1,                 //月份 
        "d+" : date.getDate(),                    //日 
        "h+" : date.getHours(),                   //小时 
        "m+" : date.getMinutes(),                 //分 
        "s+" : date.getSeconds(),                 //秒 
        "q+" : Math.floor((date.getMonth()+3)/3), //季度 
        "S"  : date.getMilliseconds()             //毫秒 
    }; 
    //(y+)匹配多个y，比如yyyy
    if(/(y+)/.test(fmt)) {
    
    
         // RegExp.$1是RegExp的一个属性,指的是与正则表达式匹配的第一个 子匹配(以括号为标志)字符串
            fmt=fmt.replace(RegExp.$1, (date.getFullYear()+"").substr(4 - RegExp.$1.length)); 
    }
     for(var k in o) {
    
    
        if(new RegExp("("+ k +")").test(fmt)){
    
    
             fmt = fmt.replace(RegExp.$1, (RegExp.$1.length==1) ? (o[k]) : (("00"+ o[k]).substr((""+ o[k]).length)));
         }
     }
    return fmt; 
   }
   console.log(format(new Date(),'yyyy/MM/dd'))//2022/09/03
   console.log(format(new Date(),'yyyy/MM/dd hh:mm:ss'))//2022/09/03 16:11:41
   console.log(format(new Date(),'mm:ss'))//18:28

You can also directly add the format method to the Date prototype

Date.prototype.format = function(fmt) {
    
     
     var o = {
    
     
        "M+" : this.getMonth()+1,                 //月份 
        "d+" : this.getDate(),                    //日 
        "h+" : this.getHours(),                   //小时 
        "m+" : this.getMinutes(),                 //分 
        "s+" : this.getSeconds(),                 //秒 
        "q+" : Math.floor((this.getMonth()+3)/3), //季度 
        "S"  : this.getMilliseconds()             //毫秒 
    }; 
    if(/(y+)/.test(fmt)) {
    
    
            fmt=fmt.replace(RegExp.$1, (this.getFullYear()+"").substr(4 - RegExp.$1.length)); 
    }
     for(var k in o) {
    
    
        if(new RegExp("("+ k +")").test(fmt)){
    
    
             fmt = fmt.replace(RegExp.$1, (RegExp.$1.length==1) ? (o[k]) : (("00"+ o[k]).substr((""+ o[k]).length)));
         }
     }
    return fmt; 
}
//使用
console.log(new Date().format("yyyy:MM:dd")//2022:09:03

2. Convert the timestamp to the format of year, month and day

//时间戳转换为yyyy-MM-dd hh:mm:ss
//timestamp(秒为单位)时间戳
export function format(timestamp) {
    
    
  var date = new Date(timestamp * 1000);
  var Y = date.getFullYear() + "-";
  var M =
    (date.getMonth() + 1 < 10
      ? "0" + (date.getMonth() + 1)
      : date.getMonth() + 1) + "-";
  var D =
    (date.getDate() < 10 ? "0" + date.getDate() : date.getDate()) + " ";
  var h =
    (date.getHours() < 10 ? "0" + date.getHours() : date.getHours()) + ":";

  var m =
    (date.getMinutes() < 10 ? "0" + date.getMinutes() : date.getMinutes()) +
    ":";
  var s =
    date.getSeconds() < 10 ? "0" + date.getSeconds() : date.getSeconds();
  return Y + M + D + h + m + s;
}

Or use it in conjunction with format after getting the date

3. Convert time to timestamp

var date = new Date('2022-9-03');

//方式一，得到的是毫秒
var time1 = date.getTime();

//方式二，得到的是毫秒
var time2 = date.valueOf();

Note: Unix timestamps are the number of seconds since January 1, 1970 (midnight UTC/GMT)