How can I determine if a variable is 'undefined' or 'null'?

Question

How do I determine if variable is undefined or null?

My code is as follows:

var EmpN         


        

Answer 1

To test if a variable is null or undefined I use the below code.

    if(typeof sVal === 'undefined' || sVal === null || sVal === ''){
      console.log('variable is undefined or null');
    }