how to stop user from scrolling when modal window open code example
Example 1: javascript disable scrolling on body
document.body.style.overflow = 'hidden';
Example 2: prevent body from scrolling when a modal is opened
$('#adminModal').modal().on('shown', function(){
$('body').css('overflow', 'hidden');
}).on('hidden', function(){
$('body').css('overflow', 'auto');
})