Here you have it with regexp:
<pre>
<script>
var re = /(\d{4}-\d{2}-\d{2}) (\d{2}:\d{2})\s*,\s*(\d{4}-\d{2}-\d{2}) (\d{2}:\d{2})/;
var str = '2014-12-05 20:00 , 2014-12-06 21:00';
var res = re.exec(str);
document.writeln(res[1]);
document.writeln(res[2]);
document.writeln(res[3]);
document.writeln(res[4]);
</script>
</pre>