Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://www.geeksforgeeks.org/javascript/javascript-boolean/ below:

JavaScript Boolean - GeeksforGeeks

Last Updated : 11 Jul, 2025

To represent logical values, JavaScript uses the Boolean data type, which has two possible values: true or false. These values often result from comparisons or logical operations. Additionally, the Boolean() function can convert other types of values into Boolean, determining their truthy or falsy nature.

The Boolean() function is used to explicitly convert a value to its Boolean equivalent. Truthy values return true, while falsy values return false.

console.log(Boolean("Hello"));
console.log(Boolean(0));    

• Non-empty strings like "Hello" are truthy.
• Zero is a falsy value.

In JavaScript, all objects, arrays, and non-empty strings are considered truthy values.

console.log(Boolean({}));
console.log(Boolean([])); 
console.log(Boolean("Hi"));

Objects and arrays always evaluate to true in Boolean contexts.

Certain values, like 0, null, undefined, NaN, and empty strings, are falsy.

console.log(Boolean("") === false); 
console.log(Boolean(undefined)); 

These values lack meaningful content and thus evaluate to false.

While JavaScript supports primitive Booleans, the Boolean constructor can create Boolean objects. However, these objects are truthy regardless of their value.

let obj = new Boolean(false);
console.log(obj);      
console.log(typeof obj); 
console.log(Boolean(obj));

[Boolean: false]
object
true

Using new Boolean() is generally discouraged because it can lead to confusion.

A Boolean primitive is a simple representation of true or false. This is the most commonly used Boolean type in JavaScript.

let isAvailable = true;
console.log(typeof isAvailable);

Boolean primitives are lightweight and efficient for logical operations.

JavaScript implicitly converts values to Boolean in contexts like conditions and loops.

let user = "";
if (user) {
    console.log("Valid input");
} else {
    console.log("Invalid input");
}

Empty strings evaluate to false, so "Invalid input" is logged.

The Boolean constructor can create Boolean objects, but primitive Booleans are preferred.

let primitiveBool = true;
let objBool = new Boolean(false);
console.log(typeof primitiveBool);
console.log(typeof objBool); 

Primitive Booleans are easier to use and avoid unnecessary complexity.

Falsy Values: Values that are evaluated as false when used in a Boolean. Unlike truthy values, falsy values represent "nothingness," "emptiness," or "failure."

• false
• 0, -0
• null
• undefined
• NaN
• '' (empty string)

Truthy Values: Values that are evaluated to be true when used in a Boolean context, such as in conditional statements or logical operations.

• Non-zero numbers (e.g., 1, -42)
• Non-empty strings (e.g., 'Hello', ' ')
• Objects and arrays ({}, [])

Truthy/Falsy in Action

console.log(Boolean(""));    
console.log(Boolean("text"));
console.log(Boolean(0));    
console.log(Boolean([]));  

false
true
false
true

• Empty strings and 0 are falsy.
• Non-empty strings and arrays are truthy.

let age = 0;
if (age) {
    console.log("Age provided");
} else {
    console.log("Age missing");
}

Since userAge is 0, it evaluates to falsy, and "Age missing" is logged.

let score = 70;
if (score >= 50) {
    console.log("Pass");
} else {
    console.log("Fail");
}

let age = 16;
let isAdult = age >= 18 ? true : false;
console.log(isAdult);

let defaultName = "Guest";
let userName = "" || defaultName;
console.log(userName);

We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript.

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4