How to detect the end of a horizontal scroll in a div?

Use scrollWidth and width along with your leftscrollwidth to get the difference. In your case there is offset of 8 so it will give the difference of 8 it may be because of your padding or margin.

var $elem=$('#scrollquestion');
var newScrollLeft = $elem.scrollLeft(),
    width=$elem.width(),
    scrollWidth=$elem.get(0).scrollWidth;
var offset=8;
if (scrollWidth- newScrollLeft-width==offset) {
    alert('right end');
}

Live Demo

Use the outerWidth() to get the offset including the width like,

var $elem=$('#scrollquestion');
var newScrollLeft = $elem.scrollLeft(),
    width=$elem.outerWidth(),
    scrollWidth=$elem.get(0).scrollWidth;
if (scrollWidth-newScrollLeft==width) {
    alert('right end');
}

Another Demo without using offset

Rohan kumar's answer is correct and works fine, but you can do this without calculating the offset manually

var newScrollLeft=$('#scrollquestion').scrollLeft();
      var divWidth = $('#scrollquestion').outerWidth();
      var scrollwidth =$('#scrollquestion').get(0).scrollWidth;
      if(newScrollLeft === scrollwidth - divWidth){
        alert('right end');
      }

For my specific case, dangor's solution with the

if ($scrollWidth - $width === $scrollLeft) {
        alert('right end');
}

did not work for me because calculating ($scrollWidth - $width) created a very small decimal that made the left-side of the comparison a float, and the right-side ($scrollLeft), an integer. Changing it to the code below works perfect for me.

if (parseInt($scrollWidth - $width) === parseInt($scrollLeft)) {
            alert('right end');
}

Try http://jsfiddle.net/trxe4n3u/3/

$(function() {
    $('#scrollquestion').scroll( function() {
        var $width = $('#scrollquestion').outerWidth()
        var $scrollWidth = $('#scrollquestion')[0].scrollWidth; 
        var $scrollLeft = $('#scrollquestion').scrollLeft();

        if ($scrollWidth - $width === $scrollLeft){
            alert('right end');
        }
        if ($scrollLeft===0){
            alert('left end');
        }
    });
});