CKEditor

HTML

<script src="http://ckeditor.com/apps/ckeditor/4.0/ckeditor.js"></script>
<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.0/css/bootstrap-combined.min.css">
<script src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.0/js/bootstrap.min.js"></script>
<div id='tiny_mce_block'>
    <textarea id="editor1"><span class="st" id="1" data-time-start="0.29" data-time-end="1.259" data-time-moy="0.1938">mardi </span>
 <span class="st" id="2" data-time-start="2.048" data-time-end="5.406" data-time-moy="0.10832258064516">qualité sécurité efficacité </span>
    </textarea>
</div>

JavaScript

var textarea;

$(document).ready(function () {
    textarea = $('#tiny_mce_block').find('textarea').attr('id');
    ckeditor_init();
});

function ckeditor_init() { // This works
    CKEDITOR.replace(textarea, {
        language: 'fr',
        allowedContent: true,
    });

    var editor = CKEDITOR.instances[textarea]; // This works
    var $dataCkeditor = editor.getData(); // This works

    var el = $(editor.document.getElementById('2')); // This doesn't work !

    alert(el);
}