Undefined Vs Null - Developer Roadmap

Undefined variables are variables that the developer has declared but not yet assigned a value.

javascript

// Example 1

let study;

console.log(study); // undefined var

// Example 2

let myObj = {}; // empty object

console.log(myObj.name); // undefined because name does not exist

A null variable is a variable or property that is empty. You use null variables when you want to show that a variable has no values or want to clear the value of a variable.

javascript

// Example 1

let study = null;

console.log(study); // null

// Example 2

let obj = {
    name: "cess",
};

obj.name = null;

console.log(obj.name); // null