How can I prevent body scrollbar and shifting when twitter bootstrap modal dialog is loaded?
When I open the twitter bootstrap modal dialog, the backdrop causes a scrollbar and shift the content.
To avoid the scrollbar I use this css:
.modal {
overflow: hidden;
}
But I can not avoid the shift.
regards, Marko
I am using Bootstrap Version 3
Answer
Marko,
I just had the same problem. It appears that Bootstrap 3.0.0 adds a class to <body>, modal-open, when the modal first shows. This class adds margin-right: 15px to the body to account for a scrollbar, which is there on longer pages. This is great, except for shorter pages when a scrollbar isn't on the body. In the no scrollbar case, the margin-right causes the body to shift left on modal open.
I was able to solve this by adding some short Javascript and a little CSS:
CSS:
/* override bootstrap 3 class to remove scrollbar from modal backdrop
when not necessary */
.modal {
overflow-y: auto;
}
/* custom class to override .modal-open */
.modal-noscrollbar {
margin-right: 0 !important;
}
JS:
(function($) {
$(document)
.on( 'hidden.bs.modal', '.modal', function() {
$(document.body).removeClass( 'modal-noscrollbar' );
})
.on( 'show.bs.modal', '.modal', function() {
// Bootstrap adds margin-right: 15px to the body to account for a
// scrollbar, but this causes a "shift" when the document isn't tall
// enough to need a scrollbar; therefore, we disable the margin-right
// when it isn't needed.
if ( $(window).height() >= $(document).height() ) {
$(document.body).addClass( 'modal-noscrollbar' );
}
});
})(window.jQuery);
These combined permit the margin-right scrollbar fix to work for long pages, yet is disabled for shorter pages (when document height <= window height). I hope this helps!
Bootstrap 3.0.1+ (tested up to 3.1.1) is a different story. Try the following:
CSS:
/* override bootstrap 3 class to remove scrollbar from modal backdrop
when not necessary */
.modal {
overflow-y: auto;
}
/* custom class to add space for scrollbar */
.modal-scrollbar {
margin-right: 15px;
}
JS:
(function($) {
$(document)
.on( 'hidden.bs.modal', '.modal', function() {
$(document.body).removeClass( 'modal-scrollbar' );
})
.on( 'show.bs.modal', '.modal', function() {
// Bootstrap's .modal-open class hides any scrollbar on the body,
// so if there IS a scrollbar on the body at modal open time, then
// add a right margin to take its place.
if ( $(window).height() < $(document).height() ) {
$(document.body).addClass( 'modal-scrollbar' );
}
});
})(window.jQuery);
EDIT:
In light of Mac eliminating scrollbars from inhabiting window render width, here's a more portable solution (3.0.1+) if you don't mind some feature detection. Reference: http://davidwalsh.name/detect-scrollbar-width
CSS:
.scrollbar-measure {
height: 100px;
overflow: scroll;
position: absolute;
top: -9999px;
}
JS:
window.jQuery(function() {
// detect browser scroll bar width
var scrollDiv = $('<div class="scrollbar-measure"></div>')
.appendTo(document.body)[0],
scrollBarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth;
$(document)
.on('hidden.bs.modal', '.modal', function(evt) {
// use margin-right 0 for IE8
$(document.body).css('margin-right', '');
})
.on('show.bs.modal', '.modal', function() {
// When modal is shown, scrollbar on body disappears. In order not
// to experience a "shifting" effect, replace the scrollbar width
// with a right-margin on the body.
if ($(window).height() < $(document).height()) {
$(document.body).css('margin-right', scrollBarWidth + 'px');
}
});
});