JavaScript Booleans

What is a Boolean?

In JavaScript, a Boolean represents one of two values:

true
false

Booleans are mainly used to make decisions in code — like controlling if something happens or not.

Creating Booleans

1. Boolean Literals

let isJavaScriptFun = true;
let isSkyGreen = false;

2. Using the Boolean() Function

let x = Boolean(10); // true
let y = Boolean(0); // false
let z = Boolean(""); // false
let a = Boolean("Hello"); // true

The Boolean() function converts any value to true or false.

Examples and Outputs

Example 1: Simple Booleans

let isAdult = true;
let isChild = false;
console.log(isAdult); // Output: true
console.log(isChild); // Output: false

Example 2: Boolean Conversion

console.log(Boolean(100)); // Output: true
console.log(Boolean(0)); // Output: false
console.log(Boolean("Hi")); // Output: true
console.log(Boolean("")); // Output: false
console.log(Boolean(undefined)); // Output: false
console.log(Boolean(null)); // Output: false

Truthy and Falsy Values

JavaScript considers some values automatically as true (truthy) and others as false (falsy).

Falsy Values	Means
	false
false	false
0	false
-0	false
"" (Empty string)	false
null	false
undefined	false
NaN	false

Everything else is considered truthy (means true).

Boolean in Conditional Statements

Booleans are very important in if, while, and other conditions.

Example:

let isLoggedIn = true;
if (isLoggedIn) {
console.log("Welcome back!");
} else {
console.log("Please log in.
");
}
// Output: Welcome back!

Comparison Operations (Return Boolean)

Operators like == , === , >, <, etc., return a boolean.

Example:

console.log(10 > 5); // Output: true
console.log(3 ===
"3"); // Output: false
console.log(3 ==
"3"); // Output: true (because == does type
conversion)
Logical Operators with Booleans
Operator Description Example Output

Logical Operators with Booleans

Operator	Description	Example	Output
&& (AND)	Both must be true	true && false	false
`		` (OR)	At least one true
! (NOT)	Reverses boolean	!true	false

Example:

console.log(true && false); // Output: false
console.log(true || false); // Output: true
console.log(!true);