方法一：
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8">
<title></title>
<script>
function dateToDate(date) {
var sDate = new Date();
if (typeof date == 'object'
&& typeof new Date().getMonth == "function"
) {
sDate = date;
}
else if (typeof date == "string") {
var arr = date.split('-')
if (arr.length == 3) {
sDate = new Date(arr[0] + '-' + arr[1] + '-' + arr[2]);
}
}
return sDate;
}
function addMonth(date, num) {
num = parseInt(num);
var sDate = dateToDate(date);
var sYear = sDate.getFullYear();
var sMonth = sDate.getMonth() + 1;
var sDay = sDate.getDate();
var eYear = sYear;
var eMonth = sMonth + num;
var eDay = sDay;
while (eMonth > 12) {
eYear++;
eMonth -= 12;
}
var eDate = new Date(eYear, eMonth - 1, eDay);
while (eDate.getMonth() != eMonth - 1) {
eDay--;
eDate = new Date(eYear, eMonth - 1, eDay);
}
return eDate;
}
function calcDate() {
var d = document.getElementById('date').value;
var n = document.getElementById('num').value;
var eDate = addMonth(d, n);
document.getElementById('result').innerHTML = eDate.getFullYear() + '-' + (eDate.getMonth() + 1) + '-' + eDate.getDate();
}
</script>
</head>
<body>
<input type="date" id="date" />
<input type="number" id="num" value="1" />
<input type="button" value="计算" onclick="calcDate()" />
<div id="result"></div>
</body>
</html>
方法二：
<script language="javascript">
Date.prototype.Format = function(fmt)
{
//代码作者: meizz
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;
}
Date.prototype.addDays = function(d)
{
this.setDate(this.getDate() + d);
};
Date.prototype.addWeeks = function(w)
{
this.addDays(w * 7);
};
Date.prototype.addMonths= function(m)
{
var d = this.getDate();
this.setMonth(this.getMonth() + m);
if (this.getDate() < d)
this.setDate(0);
};
Date.prototype.addYears = function(y)
{
var m = this.getMonth();
this.setFullYear(this.getFullYear() + y);
if (m < this.getMonth())
{
this.setDate(0);
}
};
</script>
方法三：
<script>
function DateAdd(interval,number,date)
{
/*
*--------------- DateAdd(interval,number,date) -----------------
* DateAdd(interval,number,date)
* 功能:实现VBScript的DateAdd功能.
* 参数:interval,字符串表达式，表示要添加的时间间隔.
* 参数:number,数值表达式，表示要添加的时间间隔的个数.
* 参数:date,时间对象.
* 返回:新的时间对象.
* var now = new Date();
* var newDate = DateAdd( "d ",5,now);
* author:wanghr100(灰豆宝宝.net)
* update:2004-5-28 11:46
*--------------- DateAdd(interval,number,date) -----------------
*/
switch(interval)
{
case "y " : {
date.setFullYear(date.getFullYear()+number);
return date;
break;
}
case "q " : {
date.setMonth(date.getMonth()+number*3);
return date;
break;
}
case "m " : {
date.setMonth(date.getMonth()+number);
return date;
break;
}
case "w " : {
date.setDate(date.getDate()+number*7);
return date;
break;
}
case "d " : {
date.setDate(date.getDate()+number);
return date;
break;
}
case "h " : {
date.setHours(date.getHours()+number);
return date;
break;
}
case "m " : {
date.setMinutes(date.getMinutes()+number);
return date;
break;
}
case "s " : {
date.setSeconds(date.getSeconds()+number);
return date;
break;
}
default : {
date.setDate(d.getDate()+number);
return date;
break;
}
}
}
var now = new Date();
//加五天.
var newDate = DateAdd( "d ",5,now);
alert(newDate.toLocaleDateString())
//加两个月.
newDate = DateAdd( "m ",2,now);
alert(newDate.toLocaleDateString())
//加一年
newDate = DateAdd( "y ",1,now);
alert(newDate.toLocaleDateString())
</script>
