wiki/content/20201113091424-javascript_prototypes.md

date	id	title
20201113	fd03be0e-a4c0-421f-9dd7-1bddc9dece65	JavaScript Prototypes

Description

A prototype can be seen as an object another object extends.

Syntax

let protoRabbit = {
  speak(line) {
    console.log(`The ${this.type} rabbit says '${line}'`); // : The killer rabbit says 'SKREEEE!'
  },
};
let killerRabbit = Object.create(protoRabbit);
killerRabbit.type = "killer";
killerRabbit.speak("SKREEEE!");

Object.prototype

Most objects in JavaScript eventually extend Object.prototype through parent prototype objects or directly, which provides a bunch of default methods¹.

console.log(Object.getPrototypeOf({}) == Object.prototype); // true
console.log(Object.getPrototypeOf(Object.prototype)); // null

Footnotes

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1. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object ↩︎