Javascript undefined condition
<p>Could somebody explain to me the difference between <code>if(obj.x == undefined)</code> and <code>if(typeof obj.x == 'undefined')</code></p>

<p>In some context the first one works fine, but in other I need to use the second way.</p>

<p>Questions</p>

<p>1 - What is the difference between the two condition?</p>

<p>2 - Is there a best practice?</p>
