How to check if a variable is null or empty string or all whitespace in JavaScript?

Question

I need to check to see if a variable is null or has all empty spaces or is just blank (\"\").

I have the following, but it is not working:

var addr;
         


        

Answer 1

You can use if(addr && (addr = $.trim(addr)))

This has the advantage of actually removing any outer whitespace from addr instead of just ignoring it when performing the check.

Reference: http://api.jquery.com/jQuery.trim/