001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.ajax;
018
019import org.apache.wicket.Component;
020import org.apache.wicket.ajax.attributes.AjaxCallListener;
021import org.apache.wicket.ajax.markup.html.AjaxFallbackLink;
022
023/**
024 * Decorator that can be used to cancel the regular action if ajax call was performed. This allows
025 * us to, for example, cancel the default anchor behavior (requesting href url) if an ajax call was
026 * made in the onclick event handler. Ajax call cannot be performed if javascript has been turned
027 * off or no compatible XmlHttpRequest object can be found. This decorator will make javascript
028 * return true if the ajax call was made, and false otherwise.
029 * 
030 * @see AjaxFallbackLink
031 * 
032 * @since 6.0
033 * 
034 * @author Igor Vaynberg (ivaynberg)
035 * 
036 */
037public final class CancelEventIfAjaxListener extends AjaxCallListener
038{
039        private static final long serialVersionUID = 1L;
040
041        @Override
042        public CharSequence getBeforeHandler(Component component)
043        {
044                return "if (attrs.event) { attrs.event.preventDefault(); }";
045        }
046}