概述

实例化日期有四种方式

var d = new Date();
var d = new Date(milliseconds);
var d = new Date(dateString);
var d = new Date(year, month, day, hours, minutes, seconds, milliseconds);

JavaScript 日期格式

获取方法

英文月份： "January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"

英文星期："Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"

日期设置方法

实例

创建日期

• 现在时间

var now = new Date();

• 指定日期

// 2022年5月31号 13点14分15秒
var definedDt = new Date(2022, 4, 31, 13, 14, 15);
console.info("definedDt:", definedDt);
console.info("mills:", definedDt.getTime());

// definedDt: Date Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)
// mills: 1653974055000

• 指定日期前后
  之后n天，之前n天，之后n月等等

// 之后一天
var next = new Date(1653974055000);
next.setDate(next.getDate() + 1);
console.info("next day:", next);
// 之前一天
var before = new Date(1653974055000);
before.setDate(before.getDate() - 1);
console.info("before day:", before);
// next day: Date Wed Jun 01 2022 13:14:15 GMT+0800 (中国标准时间)
// before day: Date Mon May 30 2022 13:14:15 GMT+0800 (中国标准时间)


// 5月31号 和 6月1号的下一个月都是7月1号
var may31 = new Date(2022, 4, 31);	
may31.setMonth(may31.getMonth() + 1);
console.info("next month:", may31);
var jun01 = new Date(2022, 5, 1);
jun01.setMonth(jun01.getMonth() + 1);
console.info("next month:", jun01);

// next month: Date Fri Jul 01 2022 00:00:00 GMT+0800 (中国标准时间)
// next month: Date Fri Jul 01 2022 00:00:00 GMT+0800 (中国标准时间)

格式化日期

• JS自带

var may31 = new Date(1653974055000);
console.info("toString: ",may31.toString());
console.info("toDateString: ",may31.toDateString());
console.info("toLocaleString: ",may31.toLocaleString());
console.info("toLocaleDateString: ",may31.toLocaleDateString());
console.info("toGMTString: ",may31.toGMTString());
console.info("toUTCString: ",may31.toUTCString());
console.info("toISOString: ",may31.toISOString());

// toString:  Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)
// toDateString:  Tue May 31 2022
// toLocaleString:  2022/5/31 13:14:15
// toLocaleDateString:  2022/5/31
// toGMTString:  Tue, 31 May 2022 05:14:15 GMT
// toUTCString:  Tue, 31 May 2022 05:14:15 GMT
// toISOString:  2022-05-31T05:14:15.000Z

• 自定义转换

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;
}

var may31 = new Date(1653974055123);
var r1 = may31.format("yyyy-MM-dd HH:mm:ss.S");
var r2 = may31.format("yyyy/MM/dd HH:mm:ss");
console.info("r1:", r1);
console.info("r2:", r2);

// r1: 2022-05-31 13:14:15.123
// r2: 2022/05/31 13:14:15

解析日期字符串

使用new Date(dateString)

console.info(new Date("2022-05-31 13:14:15.123"));
console.info(new Date("2022/05/31 13:14:15"));
console.info(new Date("Tue May 31 2022 13:14:15 GMT+0800"));
console.info(new Date("Tue, 31 May 2022 05:14:15 GMT"));
console.info(new Date("2022-05-31T05:14:15.000Z"));
// Date Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)
// Date Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)
// Date Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)
// Date Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)
// Date Tue May 31 2022 13:14:15 GMT+0800 (中国标准时间)