Javascript – How to determine if a 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'){
<div id="esd-names">
  <div id="name"></div>

But if I do this, the JavaScript interpreter halts execution.

Best Solution

You can use the qualities of the abstract equality operator to do this:

if (variable == null){
    // your code here.

Because null == undefined is true, the above code will catch both null and undefined.