Checking something isEmpty in Javascript?

Question

How can I check if a variable is empty in Javascript? Sorry for the stupid question, but I\'m a newbie in Javascript!

if(response.photo) is empty {
    do so         


        

Answer 1

Empty check on a JSON's key depends on use-case. For a common use-case, we can test for following:

1. Not null
2. Not undefined
3. Not an empty String ''
4. Not an empty Object {} [] (Array is an Object)

Function:

function isEmpty(arg){
  return (
    arg == null || // Check for null or undefined
    arg.length === 0 || // Check for empty String (Bonus check for empty Array)
    (typeof arg === 'object' && Object.keys(arg).length === 0) // Check for empty Object or Array
  );
}

Return true for:

isEmpty(''); // Empty String
isEmpty(null); // null
isEmpty(); // undefined
isEmpty({}); // Empty Object
isEmpty([]); // Empty Array