JavaScript : Booleans

In JavaScript, a boolean is a data type that represents a logical value, which can be either true or false. Booleans are commonly used in conditional statements, comparisons, and boolean logic operations. Here's how you can work with booleans in JavaScript:

1. Declaring Booleans:

You can declare boolean variables using the true and false keywords:

let isRaining = true; let isSunny = false;

2. Comparison Operators:

Comparison operators return boolean values based on the comparison result:

let x = 5; let y = 10;

console.log(x < y); // Output: true console.log(x === y); // Output: false

3. Conditional Statements:

Booleans are often used in conditional statements to control the flow of code execution:

let isLogged = true;

if (isLogged) { console.log('User is logged in.'); } else { console.log('User is not logged in.'); }

4. Boolean Logic Operations:

JavaScript provides logical operators ( && , || , ! ) for boolean logic operations:

&& (Logical AND): Returns true if both operands are true.
|| (Logical OR): Returns true if at least one of the operands is true.
! (Logical NOT): Returns the opposite boolean value of the operand.

let isMorning = true; let isWeekend = false;

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

5. Boolean Conversion:

You can convert other data types to booleans using the Boolean() function:

console.log(Boolean(0)); // Output: false console.log(Boolean('')); // Output: false console.log(Boolean(10)); // Output: true console.log(Boolean('hello')); // Output: true