DOM accessing element JS

Give开发者_StackOverflown the following xml

<rss>
    <channel>
    ...
    <pubDate>20/30/2099</pubDate>
    ...
    <item>
        ...
        <pubDate>10/30/2099</pubDate>
        ...
    </item>
    ...
    <item>
        ...
        <pubDate>40/30/2099</pubDate>
        ...
    </item>
    ...
    </channel>
</rss>

how would I efficiently access pudDate in channel and items as array, as well as pudDate in that array.

You could use xpath (as long as you don't need it for IE), using document.evaluate. Here's the function I use for it:

 function getFromXPath(expression,rootEl){
   rootEl = rootEl || docbody;
   var ret = [] 
             ,xresult = document.evaluate(expression, rootEl, null,
                         XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null)
             ,result = xresult.iterateNext();
   while (result) {
     ret[ret.length]= result;
     result = xresult.iterateNext();
   }
   return ret;
}

Where in your case expression could be something like "//channel/pubdate|channel/item/pubdate" (for all pubdates in the tree) or "//chanel/items" (for all item elements in the tree), and rootEl being the (xml) document root.

This function returns an array containing the elements you requested by xpath-expression.