How to check if a variable or object is undefined?
<p>I always thought I could just check an undefined var by comparing it to undefined, but this is the error I get in the chrome console :</p>

<p><img src="http://i.stack.imgur.com/7JIQm.png" alt="enter image description here"></p>

<p>How how do i check for the object jQuery being undefined ?</p>

<p>EDIT :</p>

<p><img src="http://i.stack.imgur.com/7JIQm.png" alt="enter image description here"></p>

<p>if(jQuery) is giving me problems too</p>

<p>EDIT :</p>

<p>solution :</p>

<p><code>if(window.jQuery)</code> works. 
<code>typeof(jQuery) == 'undefined'</code> works too.</p>

<p>Could anyone explain why ?</p>
