JavaScript Booleans

In JavaScript, booleans are the primitive data types that can either be true or false. For example,

const a = true;
const b = false;

Note: If you wrap true or false in a quote, then they are considered as a string.

For example,

const a = 'true';
console.log(typeof a); // string

The boolean values are mostly used for Comparison and Logical Operators. For example,

Equal to operator == returns true if the operands are equal.

console.log(5 == 6); // false

Not equal to operator != returns true if all the operands are not equal.

console.log(5 != 6); // true

Logical AND && returns true if both the operand values are true, else evaluates to false.

console.log(true && false); // false

The boolean values are used in if...else statements and for loops as well.

Here's a list of values that gets converted to specific boolean values.

Data type Boolean Value
undefined false
null false
NaN false
'' false
0 false
20 true
-20 true
'hello' true

JavaScript Boolean Methods

Here is a list of built-in boolean methods in JavaScript.

Method Description
toString() returns a boolean value by converting boolean to a string
valueOf() returns the primitive value of a boolean

Example: Using toString()

let count = false;

// converting to string
let result = count.toString();

console.log(typeof result);



Example: Using valueOf()

let count = true;

// converting to string
let result = count.valueOf();


console.log(typeof result);



JavaScript Boolean() Function

The Boolean() function is used to convert various data types to boolean values. For example,

const a = true;
console.log(Boolean(a)); // true

Everything with a value returns true. For example,

let result;
result = 20;
console.log(Boolean(result)); // true
console.log(typeof Boolean(result)); // boolean

result = -20;
console.log(Boolean(result)); // true

result = 'hello';
console.log(Boolean(result)); // true

result = {a: 1};
console.log(Boolean(result)); // true

In JavaScript, undefined, null, 0, NaN, '' converts to false. For example,

let result;
// empty string
result = Boolean('');
console.log(result); // false

result = Boolean(0);
console.log(result); // false

result = Boolean(undefined);
console.log(result); // false

result = Boolean(null);
console.log(result); // false

result = Boolean(NaN);
console.log(result); // false

Note: If you want to learn more about the boolean conversion, visit JavaScript Type Conversion.

Boolean Objects

You can also create a boolean value using the new keyword. For example,

const a = true;

// creating a boolean object
const b = new Boolean(true);

console.log(a); // true
console.log(b); // true

console.log(typeof a); // "boolean"
console.log(typeof b); // "object"

Note: It is recommended to avoid using boolean objects. Using boolean objects slows down the program.

Video: JavaScript Boolean

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