只是另一个例子，几乎是一行。

var date = new date (); console.log((date.getMonth() < 9 ?'0': ")+ (date.getMonth()+1));

$("body").delegate("select[name='package_title']", "change", function() {

    var price = $(this).find(':selected').attr('data-price');
    var dadaday = $(this).find(':selected').attr('data-days');
    var today = new Date();
    var endDate = new Date();
    endDate.setDate(today.getDate()+parseInt(dadaday));
    var day = ("0" + endDate.getDate()).slice(-2)
    var month = ("0" + (endDate.getMonth() + 1)).slice(-2)
    var year = endDate.getFullYear();

    var someFormattedDate = year+'-'+month+'-'+day;

    $('#price_id').val(price);
    $('#date_id').val(someFormattedDate);
});

来自MDN的建议:

function date_locale(thisDate, locale) {
  if (locale == undefined)
    locale = 'fr-FR';
  // set your default country above (yes, I'm french !)
  // then the default format is "dd/mm/YYY"

  if (thisDate == undefined) {
    var d = new Date();
  } else {
    var d = new Date(thisDate);
  }
  return d.toLocaleDateString(locale);
}

var thisDate = date_locale();
var dayN = thisDate.slice(0, 2);
var monthN = thisDate.slice(3, 5);
console.log(dayN);
console.log(monthN);

http://jsfiddle.net/v4qcf5x6/

使用Moment.js可以这样做:

moment(new Date(2017, 1, 1)).format('DD') // day
moment(new Date(2017, 1, 1)).format('MM') // month

更现代的方法可能是使用"padStart"

const now = new Date();
const day = `${now.getDate()}`.padStart(2, '0');
const month = `${now.getMonth()}`.padStart(2, '0');
const year = now.getFullYear();

然后，如果你愿意，你可以构建一个模板字符串:

`${day}/${month}/${year}`

("0" + this.getDate()).slice(-2)

对于日期，类似的:

("0" + (this.getMonth() + 1)).slice(-2)

这个月。