Check if a string is null or empty in XSLT

Question

How can I check if a value is null or empty with XSL?

For example, if categoryName is empty? I\'m using a when choosing construct.

For

Answer 1

Something like this works for me:

   -  
   
    
  

Or the other way around:

  
    
   
   - 

Note: If you don't check null values or handle null values, IE7 returns -2147483648 instead of NaN.