Get days left till end of the month with moment.js

If you're looking for a plain javascript version, I've wrote this function:

function getMonthDaysLeft(){
    date = new Date();
    return new Date(date.getFullYear(), date.getMonth() + 1, 0).getDate() - date.getDate();
}

You could do something like this:

var a = moment().endOf('month');
var b = moment();

if(a.diff(b, 'days') <= 13)
{
    //do something
}