Is there a standard function to check for null, undefined, or blank variables in JavaScript?

Question

Is there a universal JavaScript function that checks that a variable has a value and ensures that it\'s not undefined or null? I\'ve got this code,

Answer 1

The verbose method to check if value is undefined or null is:

return value === undefined || value === null;

You can also use the == operator but this expects one to know all the rules:

return value == null; // also returns true if value is undefined