Structure can be something like this:
<div id="textarea" contenteditable>
<p class="str selected" id="str1"><span class="tmstamp">[00:00.000]</span> String 1</p>
<p class="str" id="str2><span class="tmstamp">[00:01.000]</span> String 2</p>
<p class="str" id="str3"><span class="tmstamp">[00:02.000]</span> String 3</p>
<p class="str" id="str4"><span class="tmstamp">[00:05.000]</span> String 4</p>
<p class="str" id="str5"><span class="tmstamp">[00:10.000]</span> String 5</p>
<p class="str" id="str6"><span class="tmstamp">[01:50.457]</span> String 6</p>
...etc.
</div>