How to Know Which HTML Element is Causing Vertical Scroll Bar

Question

I am learning Bootstrap. On the getting started menu, there are few templates given. I am playing with that. One example is about fixed Footer. I used nav from previous example

Answer 1

There is an excellent article by Chris Coyier which explain everything you need about this problem.

after reading this article, I personally use this code in my console to find out which element cause vertical scroll:

press F12 in your Browser then choose console and paste the below code there and press enter:

var all = document.getElementsByTagName("*"), i = 0, rect, docWidth = document.documentElement.offsetWidth;
for (; i < all.length; i++) {
    rect = all[i].getBoundingClientRect();
    if (rect.right > docWidth || rect.left < 0){
        console.log(all[i]);
        all[i].style.border = '1px solid red';
    }
}

Update:
if the above code didn't work it might be an element inside an iframe that make the page to vertically scroll. in this case you can check iframes with this code:

var frames = document.getElementsByTagName("iframe");
for(var i=0; i < frames.length; i++){
   var frame = frames[i];
   frame = (frame.contentWindow || frame.contentDocument);
   var all = frame.document.getElementsByTagName("*"),rect,
       docWidth = document.documentElement.offsetWidth;
   for (var j =0; j < all.length; j++) {
       rect = all[j].getBoundingClientRect();
       if (rect.right > docWidth || rect.left < 0){
           console.log(all[j]);
           all[j].style.border = '1px solid red';
       }
   }
}