JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">
<img src = "http://dummyimage.com/120x90/f00/fff.png&text=my+image" />

JavaScript

var xml = "<response xmlns:ns='http://example.com/ex/'>\
  <response>SUCCESS</response>\
  <action>QUERY</action>\
  <data>\
    <ns:blah>Trying to reach me!</ns:blah>\
  </data>\
</response>";

var blah = $(xml).find('ns\\:blah');

alert('found: ' + blah.length);