javascript实现日期按月份加减
原文：https://www.jb51.net/article/66132.htm
<!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>
