Q:

Why the javascript package of bootstrap does't work?

I have bootstrap in my website, and I have import all the "bootstrap.min.css" "bootstrap.js" and "jquery.js" file into my html file. however code following doesn't work! Anyone can help me out?
<button type="button" class="btn btn-default" data-toggle="tooltip" data-placement="left" title="Tooltip on left">Tooltip on left</button>

A:

Please check this jsfiddle:
http://jsfiddle.net/5bq8U/
HTML:
<div align="center">
    <button type="button" class="btn btn-default" data-toggle="tooltip" data-placement="left" title="Tooltip on left">Tooltip on left</button>
</div>

JS:
$('button').tooltip();

