Dojo fiddle

This JSFiddle is configured and ready to use for testing the Dojo framework.

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/dojo/1.9.1/dijit/themes/claro/claro.css">
<p class="mainText" data-lang="es">Welcome</p>

JavaScript

require([ "dojo/query", "dojo/NodeList-dom", "dojo/domReady!" ], function(query) {
    query("[data-lang]").forEach(function(item){
        alert(query(item).attr("innerHTML")[0]);
    });
});