gistfile1.js

attr: function( elem, name, value, pass ) {
		var nType = elem.nodeType;
		
		// don't get/set attributes on text, comment and attribute nodes
		if ( !elem || nType === 3 || nType === 8 || nType === 2 ) {
			return undefined;
		}

		if ( pass && name in jQuery.attrFn ) {
			return jQuery( elem )[ name ]( value );
		}

		// Fallback to prop when attributes are not supported
		if ( !("getAttribute" in elem) ) {
			return jQuery.prop( elem, name, value );
		}

		var ret, hooks,
			notxml = nType !== 1 || !jQuery.isXMLDoc( elem );

		// Normalize the name if needed
		if ( notxml ) {
			name = jQuery.attrFix[ name ] || name;

			hooks = jQuery.attrHooks[ name ];

			if ( !hooks ) {
				// Use boolHook for boolean attributes
				if ( rboolean.test( name ) ) {
					hooks = boolHook;

				// Use nodeHook if available( IE6/7 )
				} else if ( nodeHook ) {
					hooks = nodeHook;
				}
			}
		}

		if ( value !== undefined ) {

			if ( value === null ) {
				jQuery.removeAttr( elem, name );
				return undefined;

			} else if ( hooks && "set" in hooks && notxml && (ret = hooks.set( elem, value, name )) !== undefined ) {
				return ret;

			} else {
				elem.setAttribute( name, "" + value );
				return value;
			}

		} else if ( hooks && "get" in hooks && notxml && (ret = hooks.get( elem, name )) !== null ) {
			return ret;

		} else {

			ret = elem.getAttribute( name );

			// Non-existent attributes return null, we normalize to undefined
			return ret === null ?
				undefined :
				ret;
		}
	}