How to determine if variable is 'undefined' or 'null'?

How do I determine if variable is undefined or null? My code is as follows:
var EmpName = $("div#esd-names div#name").attr('class');
if(EmpName == 'undefined'){
  //DO SOMETHING
};
<div id="esd-names">
  <div id="name"></div>
</div>
But if I do this, the JavaScript interpreter halts execution.


Answer:

You can do this:
if (variable == null){
    // your code here.
}
Check MDN for details on equality tests in JS. null == undefined is true, but null === undefinedis false. Thus the code above, as is, will catch both undefined and null.


http://stackoverflow.com/questions/2647867/how-to-determine-if-variable-is-undefined-or-null

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