null" < "undefined code example

Example 1: null + undefined

console.log(null === null);  // true
  console.log(undefined === undefined);  // true
  console.log(null + undefined === null + undefined); // false

// null + undfined equals NaN, and NaN isn't equal to itself :(

Example 2: null undefined

Undefined  used for unintentionally missing values.

Null       used for intentionally missing values.