JavaScript: Boolean, Null, Undefined

Level : Beginner

Mentor: Shailendra Chauhan

Duration : 00:00:50

JavaScript Booleans:

Booleans in JavaScript represent true or false values, used for logical operations and conditional statements.

let isTrue = true;
let isFalse = false;

The Boolean() function converts a value into a Boolean value, returning true for truthy values and false for falsy values.

let value = "Hello";
let isTruthy = Boolean(value); // true
let anotherValue = 0;
let isFalsy = Boolean(anotherValue); // false

JavaScript uses comparisons and conditions to determine the flow of a program based on Boolean results.

let x = 5;
let y = 10;
if (x < y) {
  console.log("x is less than y"); // Output: "x is less than y"
}

In JavaScript, values that have data are considered truthy, even if they are not explicitly set to true.

let nonEmptyString = "Hello";
if (nonEmptyString) {
  console.log("This will be executed"); // Output: "This will be executed"
}

Values that are empty, null, undefined, 0, NaN, or an empty string are considered falsy in JavaScript.

let emptyString = "";
if (!emptyString) {
  console.log("This will be executed"); // Output: "This will be executed"
}

JavaScript allows Booleans to be represented as objects, which can have properties and methods.

let booleanObj = new Boolean(true);
console.log(booleanObj.valueOf()); // Output: true

null is a special value in JavaScript that represents the intentional absence of any object value.

let value = null;

undefined is a value that indicates a variable has been declared but not assigned a value or a property doesn't exist.

let x;
console.log(x); // Output: undefined

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