JavaScript Boolean prototype Constructor

JavaScript Boolean Reference JavaScript Boolean Reference


Make a new method for JavaScript booleans:

Boolean.prototype.myColor = function() {
    if (this.valueOf() == true) {
        return "green";
    } else {
        return = "red";

Create a boolean, then call myColor():

var a = true;
var b = a.myColor();

The value of b is now:


Try it yourself »

Definition and Usage

The prototype constructor allows you to add new properties and methods to JavaScript booleans.

When constructing a property, ALL booleans will be given the property, and it's value, as default.

When constructing a method, ALL booleans will have this method available.

Note: Boolean.prototype does not refer to a single boolean, but to the Boolean() object itself.

Note: Prototype is a global object constructor which is available for all JavaScript objects.

Browser Support

prototype Yes Yes Yes Yes Yes

Syntax = value

JavaScript Boolean Reference JavaScript Boolean Reference


Color Picker