xml - 查明 AS3 的 XMLList 是否包含字符串作为节点值

Question

有没有等同于 Array.indexOf 的 XMLList？

例如——

var array:Array = ['one','two'];
trace(array.indexOf('two')); // returns 1, since it's at the second position
trace(array.indexOf('three')); // returns -1, since it isn't found

……对吧？但如果我有这个怎么办 -

var xml:XML = <list><item>one</item><item>two</item><list>
var xmlList:XMLList = list.item;

必须有一种比遍历所有节点更简单的方法来检查 XMLList 中的某个节点是否具有特定值，对吗？类似于 -

xmlList.indexOfChildByNodeValue('two'); // returns 1, because it's the second child
xmlList.indexOfChildByNodeValue('three'); // returns -1, because it doesn't match any children

有道理吗？

Answer 1

我整理了一个演示，说明如何在不循环的情况下进行操作。尽管它确实需要更多的前期工作。不过，如果您要经常检查值，它会带来返回。

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" applicationComplete="_init();">
    <fx:Declarations>
        <fx:XML id="movieList" source="http://www.movies.com/rss-feeds/jen-yamato-reviews-rss" />
    </fx:Declarations>
    <fx:Script>
        <![CDATA[
            import mx.logging.ILogger;
            import mx.logging.Log;
            import mx.logging.LogEventLevel;
            import mx.logging.targets.TraceTarget;

            public static const MOVIE_TITLE:String = "Inception";

            private var _logger:ILogger = Log.getLogger("Sandbox");

            private function _init() :void
            {
                var traceTarget:TraceTarget = new TraceTarget();
                traceTarget.level = LogEventLevel.ALL;
                Log.addTarget(traceTarget);

                var xmlList:XMLList = movieList..item;

                var firstItem:XML = movieList..item[0];
                var firstItemIndex:int = firstItem.childIndex();
                _logger.info("First Item Index: " + firstItemIndex);

                var item:XML = xmlList.(title == MOVIE_TITLE)[0];
                _logger.info("Contains: " + xmlList.contains(item) + " // " + item.childIndex());

                var actualIndex:int = (item.childIndex() - firstItemIndex);
                _logger.info("Actual Index: " + actualIndex);

                _logger.info("Result: " + xmlList[actualIndex]);
            }
        ]]>
    </fx:Script>

</s:Application>

基本思想是存储第一个 item 的索引，然后使用 E4X 搜索从匹配结果的 childIndex() 中减去它。