JavaScript Nullish Coalescing & Logical OR

📘 Introduction

The Nullish Coalescing Operator (??) and the Logical OR Operator (||) are used to provide default values when a variable is null, undefined, or falsy.

🔹 Nullish Coalescing Operator (??)

Returns the right-hand value if the left-hand value is null or undefined.

let user;
let name = user ?? 'Guest';
console.log(name); // 'Guest'

🔹 Logical OR Operator (||)

Returns the right-hand value if the left-hand value is falsy (0, '', null, undefined, false, NaN).

let user = '';
let name = user || 'Guest';
console.log(name); // 'Guest'
⚠️ OR treats 0, false, and '' as falsy, while Nullish Coalescing only treats null and undefined as nullish.

🧪 Try It Yourself

Click the button to see Nullish Coalescing and Logical OR in action: