JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tbody>
        <tr>
            <td>.find("feed").children("im\\:rating")</td>
            <td id="result1"></td>
        </tr>
        <tr>
            <td>.find("feed").children("jn\\:rating")</td>
            <td id="result2"></td>
        </tr>
        <tr>
            <td>getElementsByTagNameNS("http://itunes.apple.com/rss/im", "rating")</td>
            <td id="result3"></td>
        </tr>
        <tr>
            <td>getElementsByTagNameNS("http://itunes.apple.com/rss/jn", "rating")</td>
            <td id="result4"></td>
        </tr>
    </tbody>
</table>

CSS

td {
    border: solid 1px #666;
    margin:0;
    padding: 10px;
}
td:nth-of-type(1) {
    background: #ddd;
}
.blue {
    color: #fff;
    background: #00f;
}
.red {
    color: #fff;
    background: #f00;
}

JavaScript

var xml = '<feed xmlns:im="http://itunes.apple.com/rss/im"'
             + ' xmlns:jn="http://itunes.apple.com/rss/jn">'
             + '<im:rating>hogehoge1</im:rating>'
             + '<jn:rating>hogehoge2</jn:rating>'
        + '</feed>';

var xmldoc = $.parseXML(xml);

// jQuery .children([selector])
append("#result1", $(xmldoc).find("feed").children("im\\:rating").text());
append("#result2", $(xmldoc).find("feed").children("jn\\:rating").text());

// DOM getElementsByTagNameNS(ns, name)  (IE <9 not supported)
append("#result3", xmldoc.getElementsByTagNameNS("http://itunes.apple.com/rss/im", "rating")[0].childNodes[0].nodeValue);
append("#result4", xmldoc.getElementsByTagNameNS("http://itunes.apple.com/rss/jn", "rating")[0].childNodes[0].nodeValue);

function append(name, result) {
    if (!$.isEmptyObject(result)) {
        $(name).addClass("blue");
    } else {
        $(name).addClass("red");
        result = "NG";
    }
    $(name).append(result);
}