jquery/src/css.js

// exclude the following css properties to add px
var exclude = /z-?index|font-?weight|opacity|zoom|line-?height/i,
	// cache check for defaultView.getComputedStyle
	getComputedStyle = document.defaultView && document.defaultView.getComputedStyle,
	// normalize float css property
	styleFloat = jQuery.support.cssFloat ? "cssFloat" : "styleFloat";

jQuery.fn.css = function( name, value ) {
	var options = name, isFunction = jQuery.isFunction( value );

	if ( typeof name === "string" ) {
		// Are we setting the style?
		if ( value === undefined ) {
			return this.length ?
				jQuery.css( this[0], name ) :
				null;

		// Convert name, value params to options hash format
		} else {
			options = {};
			options[ name ] = value;
		}
	}

	// For each element...
	for ( var i = 0, l = this.length; i < l; i++ ) {
		var elem = this[i];

		// Set all the styles
		for ( var prop in options ) {
			value = options[prop];

			if ( isFunction ) {
				value = value.call( elem, i );
			}

			if ( typeof value === "number" && !exclude.test(prop) ) {
				value = value + "px";
			}

			jQuery.style( elem, prop, value );
		}
	}

	return this;
};

jQuery.extend({
	style: function( elem, name, value ) {
		// don't set styles on text and comment nodes
		if (!elem || elem.nodeType == 3 || elem.nodeType == 8)
			return undefined;

		// ignore negative width and height values #1599
		if ( (name == 'width' || name == 'height') && parseFloat(value) < 0 )
			value = undefined;

		var style = elem.style || elem, set = value !== undefined;

		// IE uses filters for opacity
		if ( !jQuery.support.opacity && name == "opacity" ) {
			if ( set ) {
				// IE has trouble with opacity if it does not have layout
				// Force it by setting the zoom level
				style.zoom = 1;

				// Set the alpha filter to set the opacity
				style.filter = (style.filter || "").replace( /alpha\([^)]*\)/, "" ) +
					(parseInt( value ) + '' == "NaN" ? "" : "alpha(opacity=" + value * 100 + ")");
			}

			return style.filter && style.filter.indexOf("opacity=") >= 0 ?
				(parseFloat( style.filter.match(/opacity=([^)]*)/)[1] ) / 100) + '':
				"";
		}

		// Make sure we're using the right name for getting the float value
		if ( /float/i.test( name ) )
			name = styleFloat;

		name = name.replace(/-([a-z])/ig, function(all, letter){
			return letter.toUpperCase();
		});

		if ( set )
			style[ name ] = value;

		return style[ name ];
	},

	css: function( elem, name, force, extra ) {
		if ( name == "width" || name == "height" ) {
			var val, props = { position: "absolute", visibility: "hidden", display:"block" }, which = name == "width" ? [ "Left", "Right" ] : [ "Top", "Bottom" ];

			function getWH() {
				val = name == "width" ? elem.offsetWidth : elem.offsetHeight;

				if ( extra === "border" )
					return;

				jQuery.each( which, function() {
					if ( !extra )
						val -= parseFloat(jQuery.curCSS( elem, "padding" + this, true)) || 0;
					if ( extra === "margin" )
						val += parseFloat(jQuery.curCSS( elem, "margin" + this, true)) || 0;
					else
						val -= parseFloat(jQuery.curCSS( elem, "border" + this + "Width", true)) || 0;
				});
			}

			if ( elem.offsetWidth !== 0 )
				getWH();
			else
				jQuery.swap( elem, props, getWH );

			return Math.max(0, Math.round(val));
		}

		return jQuery.curCSS( elem, name, force );
	},

	curCSS: function( elem, name, force ) {
		var ret, style = elem.style;

		// IE uses filters for opacity
		if ( !jQuery.support.opacity && name == "opacity" ) {
			ret = style.filter && style.filter.indexOf("opacity=") >= 0 ?
				(parseFloat( style.filter.match(/opacity=([^)]*)/)[1] ) / 100) + '':
				"";

			return ret === "" ?
				"1" :
				ret;
		}

		// Make sure we're using the right name for getting the float value
		if ( /float/i.test( name ) )
			name = styleFloat;

		if ( !force && style && style[ name ] ) {
			ret = style[ name ];

		} else if ( getComputedStyle ) {

			// Only "float" is needed here
			if ( /float/i.test( name ) )
				name = "float";

			name = name.replace( /([A-Z])/g, "-$1" ).toLowerCase();

			var computedStyle = elem.ownerDocument.defaultView.getComputedStyle( elem, null );

			if ( computedStyle )
				ret = computedStyle.getPropertyValue( name );

			// We should always get a number back from opacity
			if ( name == "opacity" && ret == "" )
				ret = "1";

		} else if ( elem.currentStyle ) {
			var camelCase = name.replace(/\-(\w)/g, function(all, letter){
				return letter.toUpperCase();
			});

			ret = elem.currentStyle[ name ] || elem.currentStyle[ camelCase ];

			// From the awesome hack by Dean Edwards
			// http://erik.eae.net/archives/2007/07/27/18.54.15/#comment-102291

			// If we're not dealing with a regular pixel number
			// but a number that has a weird ending, we need to convert it to pixels
			if ( !/^\d+(px)?$/i.test( ret ) && /^\d/.test( ret ) ) {
				// Remember the original values
				var left = style.left, rsLeft = elem.runtimeStyle.left;

				// Put in the new values to get a computed value out
				elem.runtimeStyle.left = elem.currentStyle.left;
				style.left = ret || 0;
				ret = style.pixelLeft + "px";

				// Revert the changed values
				style.left = left;
				elem.runtimeStyle.left = rsLeft;
			}
		}

		return ret;
	},

	// A method for quickly swapping in/out CSS properties to get correct calculations
	swap: function( elem, options, callback ) {
		var old = {};
		// Remember the old values, and insert the new ones
		for ( var name in options ) {
			old[ name ] = elem.style[ name ];
			elem.style[ name ] = options[ name ];
		}

		callback.call( elem );

		// Revert the old values
		for ( var name in options )
			elem.style[ name ] = old[ name ];
	}
});