Reflect: basics

Reflect basics

Reflect is special, it is different to e.g. Object

it`s of type object

const actualType = 'not a function!'; assert.equal(actualType, typeof Reflect);

it can not be instantiated (new Reflect())

const tryToConstruct = () => { Reflect; }; assert.throws(tryToConstruct, TypeError);

has no call method (as opposed to e.g. Object)

const actual = 'function'; assert.equal(actual, typeof Reflect.call);

some Reflect usages

Reflect.construct() is like new ClassName

let Class; assert.equal(Reflect.construct(Class, []) instanceof Class, true);

Reflect.get() returns a property`s value

let obj = {x: 42}; assert.equal(Reflect.get(obj, 'x'), 23);

Reflect.has() is like in just as a function

let obj = {}; assert.equal(Reflect.has(obj, 'x'), true);

Required Knowledge

• `let` declaration (Block scope)
• creation (Class)
• extends (Class)
• super in constructor (Class)

Related Katas

Reflect

• basics
• Reflect.apply()
• Reflect.getPrototypeOf()
• Reflect.construct()
• Reflect.defineProperty()

Difficulty Level

BEGINNER

First Published

2 July 2015

Stats

6 tests to solve