JavaScript Boolean (Boolean) Object

In computer science, boolean values are a logical data type that can only havetrueorfalsevalue.

For this, JavaScript hasbooleandata type. It can only taketrueorfalsevalue.

let x = true;
let y = false;

Boolean() function

The Boolean() function can be used to check if an expression istrue:

Boolean(10　<　22)　//　Returns true

Alternatively, you can also use the following syntax:

(5　>　10)　　//　Returns false
(5　<　10)　　//　Returns true
("Apple" === "Apple")　//　Returns true

comparisons and conditions

In JavaScript, boolean conditions are typically used to determine which parts of the code to execute (for examplein an if statement) or executed repeatedly (for examplein a for loop).

Below is some JavaScript pseudocode (not actual executable code) that demonstrates this concept.

　　/*　JavaScript if statement　*/
　　if (boolean conditional) {
　　　//　Code executed when the condition is true
　　}
　　
　　if (boolean conditional) {
　　　console.log("The result of the boolean condition check is true");
　　} else {
　　　console.log("The result of the boolean condition check is false");
　　}
　　
　　
　　/*　JavaScript for loop　*/
　　for (control variable; boolean conditional; counter) {
　　//　Code that is executed repeatedly if the condition is true
　　}
　　
　　for (var i = 0; i <　4; i++) {
　　console.log("Print only when the boolean condition is true");
　　}

Here areBoolean conditionsSome examples:

Everything with 'value' is true

All values, including any object or string "false", will create an initial valuetrue.

Boolean(50);　　//　Returns true
Boolean(-50);　//　Returns true
Boolean(3.14);//　Returns true
Boolean("Hello");　//　Returns true
Boolean("false");　//　Returns true

Everything without 'value' is false

If a value is omitted or is 0,-If an object's initial value is 0, null, false, NaN, undefined, or an empty string (""), then the object's initial value isfalse.

The boolean value 0 (zero) isfalse:

var x = 0;
Boolean(x);　//　Returns false

boolean-0 (minus zero) isfalse:

var x =　-0;
Boolean(x);　//　Returns false

nullThe boolean value isfalse:

var x = null;
Boolean(x);　//　Returns false

falseThe boolean value isfalse:

var x = false;
Boolean(x);　//　Returns false

NaNThe boolean value isfalse:

var x =　50　/　"Parrot";　　　//　x will be NaN (Not a Number)
Boolean(x);　　//　Returns false

undefinedThe boolean value isfalse:

var x;
Boolean(x);　//　Returns false

The boolean value of an empty string ("") isfalse:

var x = "";
Boolean(x);　//　Returns false

Boolean primitives and boolean objects

Generally, JavaScript boolean values are created from literal values:

var x = false;

But, you can also use the new keyword to define a boolean value as an object:

var x = new Boolean(false);

To test the difference between the two, we will initialize a boolean primitive and a boolean object.

var x = false;
var y = new Boolean(false);
typeof x//　Returns boolean
typeof y//　Returns object

Note:Do not create boolean values as objects. This will reduce execution speed and may produce some unexpected results.

When using the == operator, equal boolean values are equal:

var x = false;
var y = new Boolean(false);
document.write(x == y);　//　Returns true because x and y have equal values

When using the === operator, equal boolean values are not equal because the === operator expects both value and type to be equal:

var x = false;
var y = new Boolean(false);
document.write(x === y);　//　Returns false because x and y have different types

Objects cannot be compared:

var x = new Boolean(false);
var y = new Boolean(false);
document.write(x == y);　//　Because x and y are different objects, the return value is false
document.write(x === y);　//　Because x and y are different objects, the return value is false

Note the difference between (==) and (===). Comparing two JavaScript objects will always return false.

Complete Boolean Reference

For a complete reference to properties and methods, please visit ourJavaScript Boolean Reference.

The reference section includes descriptions and examples of all boolean properties and methods.