JavaScript String prototype

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Example

Use the prototype property to add a new property to all objects of a given type:

function employee(name, jobtitle, born) {
this.name = name;
this.jobtitle = jobtitle;
this.born = born;
}
employee.prototype.salary = 2000;

const fred = new employee("Fred Flintstone", "Caveman", 1970);

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Definition and Usage

The prototype is a property available with all JavaScript objects.

The prototype property allows you to add new properties and methods to strings.

Syntax

object.prototype.name = value

Warning

You are not advised to change the prototype of an object that you do not control.

You should not change the prototype of built in JavaScript datatypes like:

Numbers
Strings
Arrays
Dates
Booleans
Function
Objects

Only change the prototype of your own objects.

The prototype Property

The JavaScript prototype property allows you to add new properties to objects:

Example

function Person(first, last, age, eyecolor) {
this.firstName = first;
this.lastName = last;
this.eyeColor = eyecolor;
}

Person.prototype.nationality = "English";

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