jquery/src/dimensions.js

(function( jQuery ) {

// Create innerHeight, innerWidth, outerHeight and outerWidth methods
jQuery.each([ "Height", "Width" ], function( i, name ) {

	var type = name.toLowerCase();

	// innerHeight and innerWidth
	jQuery.fn["inner" + name] = function() {
		return this[0] ?
			parseFloat( jQuery.css( this[0], type, "padding" ) ) :
			null;
	};

	// outerHeight and outerWidth
	jQuery.fn["outer" + name] = function( margin ) {
		return this[0] ?
			parseFloat( jQuery.css( this[0], type, margin ? "margin" : "border" ) ) :
			null;
	};

	jQuery.fn[ type ] = function( size ) {
		// Get window width or height
		var elem = this[0];
		if ( !elem ) {
			return size == null ? null : this;
		}

		if ( jQuery.isFunction( size ) ) {
			return this.each(function( i ) {
				var self = jQuery( this );
				self[ type ]( size.call( this, i, self[ type ]() ) );
			});
		}

		if ( jQuery.isWindow( elem ) ) {
			// Everyone else use document.documentElement or document.body depending on Quirks vs Standards mode
			// 3rd condition allows Nokia support, as it supports the docElem prop but not CSS1Compat
			var docElemProp = elem.document.documentElement[ "client" + name ];
			return elem.document.compatMode === "CSS1Compat" && docElemProp ||
				elem.document.body[ "client" + name ] || docElemProp;

		// Get document width or height
		} else if ( elem.nodeType === 9 ) {
			// Either scroll[Width/Height] or offset[Width/Height], whichever is greater
			return Math.max(
				elem.documentElement["client" + name],
				elem.body["scroll" + name], elem.documentElement["scroll" + name],
				elem.body["offset" + name], elem.documentElement["offset" + name]
			);

		// Get or set width or height on the element
		} else if ( size === undefined ) {
			var orig = jQuery.css( elem, type ),
				ret = parseFloat( orig );

			return jQuery.isNaN( ret ) ? orig : ret;

		// Set the width or height on the element (default to pixels if value is unitless)
		} else {
			return this.css( type, typeof size === "string" ? size : size + "px" );
		}
	};

});

})( jQuery );