var a=new Date();
a.setDate(a.getDate()+5);

如上所述的方法，您可以添加月到日期功能。

考虑到这些答案中没有一个会在月份变化时解释当年的情况，你可以在下面找到我做的一个答案，它应该可以处理这个问题:

方法:

Date.prototype.addMonths = function (m) {
    var d = new Date(this);
    var years = Math.floor(m / 12);
    var months = m - (years * 12);
    if (years) d.setFullYear(d.getFullYear() + years);
    if (months) d.setMonth(d.getMonth() + months);
    return d;
}

用法:

return new Date().addMonths(2);

只是在已接受的答案和评论上加上一点。

var x = 12; //or whatever offset
var CurrentDate = new Date();

//For the very rare cases like the end of a month
//eg. May 30th - 3 months will give you March instead of February
var date = CurrentDate.getDate();
CurrentDate.setDate(1);
CurrentDate.setMonth(CurrentDate.getMonth()+X);
CurrentDate.setDate(date);

这个函数处理边缘情况，并且速度很快:

function addMonthsUTC (date, count) {
  if (date && count) {
    var m, d = (date = new Date(+date)).getUTCDate()

    date.setUTCMonth(date.getUTCMonth() + count, 1)
    m = date.getUTCMonth()
    date.setUTCDate(d)
    if (date.getUTCMonth() !== m) date.setUTCDate(0)
  }
  return date
}

测试:

> d = new Date('2016-01-31T00:00:00Z');
Sat Jan 30 2016 18:00:00 GMT-0600 (CST)
> d = addMonthsUTC(d, 1);
Sun Feb 28 2016 18:00:00 GMT-0600 (CST)
> d = addMonthsUTC(d, 1);
Mon Mar 28 2016 18:00:00 GMT-0600 (CST)
> d.toISOString()
"2016-03-29T00:00:00.000Z"

非utc日期更新:(由A.Hatchkins编写)

function addMonths (date, count) {
  if (date && count) {
    var m, d = (date = new Date(+date)).getDate()

    date.setMonth(date.getMonth() + count, 1)
    m = date.getMonth()
    date.setDate(d)
    if (date.getMonth() !== m) date.setDate(0)
  }
  return date
}

测试:

> d = new Date(2016,0,31);
Sun Jan 31 2016 00:00:00 GMT-0600 (CST)
> d = addMonths(d, 1);
Mon Feb 29 2016 00:00:00 GMT-0600 (CST)
> d = addMonths(d, 1);
Tue Mar 29 2016 00:00:00 GMT-0600 (CST)
> d.toISOString()
"2016-03-29T06:00:00.000Z"

addDateMonate : function( pDatum, pAnzahlMonate )
{
    if ( pDatum === undefined )
    {
        return undefined;
    }

    if ( pAnzahlMonate === undefined )
    {
        return pDatum;
    }

    var vv = new Date();

    var jahr = pDatum.getFullYear();
    var monat = pDatum.getMonth() + 1;
    var tag = pDatum.getDate();

    var add_monate_total = Math.abs( Number( pAnzahlMonate ) );

    var add_jahre = Number( Math.floor( add_monate_total / 12.0 ) );
    var add_monate_rest = Number( add_monate_total - ( add_jahre * 12.0 ) );

    if ( Number( pAnzahlMonate ) > 0 )
    {
        jahr += add_jahre;
        monat += add_monate_rest;

        if ( monat > 12 )
        {
            jahr += 1;
            monat -= 12;
        }
    }
    else if ( Number( pAnzahlMonate ) < 0 )
    {
        jahr -= add_jahre;
        monat -= add_monate_rest;

        if ( monat <= 0 )
        {
            jahr = jahr - 1;
            monat = 12 + monat;
        }
    }

    if ( ( Number( monat ) === 2 ) && ( Number( tag ) === 29 ) )
    {
        if ( ( ( Number( jahr ) % 400 ) === 0 ) || ( ( Number( jahr ) % 100 ) > 0 ) && ( ( Number( jahr ) % 4 ) === 0 ) )
        {
            tag = 29;
        }
        else
        {
            tag = 28;
        }
    }

    return new Date( jahr, monat - 1, tag );
}


testAddMonate : function( pDatum , pAnzahlMonate )
{
    var datum_js = fkDatum.getDateAusTTMMJJJJ( pDatum );
    var ergebnis = fkDatum.addDateMonate( datum_js, pAnzahlMonate );

    app.log( "addDateMonate( \"" + pDatum + "\", " + pAnzahlMonate + " ) = \"" + fkDatum.getStringAusDate( ergebnis ) + "\"" );
},


test1 : function()
{
    app.testAddMonate( "15.06.2010",    10 );
    app.testAddMonate( "15.06.2010",   -10 );
    app.testAddMonate( "15.06.2010",    37 );
    app.testAddMonate( "15.06.2010",   -37 );
    app.testAddMonate( "15.06.2010",  1234 );
    app.testAddMonate( "15.06.2010", -1234 );
    app.testAddMonate( "15.06.2010",  5620 );
    app.testAddMonate( "15.06.2010", -5120 );

}

正如大多数答案突出显示的那样，我们可以使用setMonth()方法和getMonth()方法一起为给定的日期添加特定的月份数。

例子:(@ChadD在他的回答中提到。)

Var x = 12;//或任何偏移量 var CurrentDate = new Date(); CurrentDate.setMonth(CurrentDate.getMonth() + x);

但是我们应该小心地使用这个解决方案，因为我们会在边界情况下遇到麻烦。

要处理边缘情况，下面链接中给出的答案是有帮助的。 https://stackoverflow.com/a/13633692/3668866