width

width() ⇒ number
width(value) ⇒ self
width(function(index, oldWidth){ ... }) ⇒ self

Get the width of the first element in the collection; or set the width of all elements in the collection.

$('#foo').width()   // => 123
$(window).width()   // => 768 (viewport width)
$(document).width() // => 768