What is the major difference between $(window).width() vs $(document).width() in jQuery?
Whether window denotes the browser and document represents
From the documentation of width():
This method is also able to find the width of the window and document.
$(window).width(); // returns width of browser viewport $(document).width(); // returns width of HTML document
Simple jsFiddle Demo
In the demo, I have set html { width: 1000px; }, which is bigger than the viewport.
The width of the body of your HTML page is a third value. $('body').width() can also differ from the other two (try body { margin: 100px; } for example).