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CSSStyleDeclaration JS Conversion


JavaScript String prototype

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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Browser Support

prototype is an ECMAScript1 (ES1) feature.

ES1 (JavaScript 1997) is fully supported in all browsers:

Chrome Edge Firefox Safari Opera IE
Yes Yes Yes Yes Yes Yes