Description

The JavaScript Boolean property prototype allows the addition of new properties and methods to booleans.

The property prototype is a basic property that is available on all JavaScript objects.

However, it is recommended not to change the prototype of built-in data types, like Strings, Numbers, Booleans, Arrays, Functions, Objects, Dates, etc.,

Syntax

The property prototype has the below syntax, where bool is a boolean value.

Boolean.prototype.name = value;

Parameters

The property constructor doesn't accept any parameters.

Result

The method constructor the function that created the Boolean prototype.

Example 1: Adding a New Property

The below example shows how a new property can be added to a JavaScript boolean.

// Add a new property for JavaScript booleans
Boolean.prototype.myColor = "green";

// Create a boolean
var bool = true;

// Call the newly added method that returns the color
document.write(bool);            // Prints: true
document.write(bool.myColor);    // Prints: green

Output:

true
green

Example 2: Adding a New Method

The below example shows how a new method can be added to a JavaScript boolean.

// Add a new method for JavaScript booleans
Boolean.prototype.myColor = function() {
    if (this.valueOf() == true) {
        return "green";
    } else {
        return "red";
    }
};

// Create a boolean
var bool = true;

// Call the newly added method that returns the color
document.write(bool);             // Prints: true
document.write(bool.myColor());   // Prints: green

Output:

true
green

Browser Support

This property is introduced with ES1 (ECMAScript 1) in 1997.

It is supported in all modern browsers, like Google Chrome, Internet Explorer or Edge, Firefox, Apple Safari, Opera, etc.,

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