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Code Completion 16 Challenges

JavaScript Classes — Code Completion

Practice class declarations, constructors, inheritance, public and private elements, and static initialization.

Challenge 1

Declare a class named User.

javascript Your answer 
const User = ;

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Challenge 2

Add a constructor that stores name.

javascript Your answer 
class User {  }

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Challenge 3

Construct a User instance.

javascript Your answer 
const user = ("Ada");

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Challenge 4

Declare a shared instance method.

javascript Your answer 
class User { () { return this.name; } }

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Challenge 5

Declare a static method.

javascript Your answer 
class Box { () { return 1; } }

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Challenge 6

Declare a public instance field.

javascript Your answer 
class Score {  = 0; }

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Challenge 7

Declare a private field.

javascript Your answer 
class Wallet {  = 0; }

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Challenge 8

Declare a private method.

javascript Your answer 
class Parser { () { return true; } }

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Challenge 9

Create a subclass of Animal.

javascript Your answer 
class Dog  Animal {}

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Challenge 10

Initialize the base class in a derived constructor.

javascript Your answer 
constructor(name) { (name); }

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Challenge 11

Call the inherited method.

javascript Your answer 
speak() { return .speak() + " bark"; }

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Challenge 12

Check whether obj carries the declaring private name.

javascript Your answer 
hasValue(obj) { return  in obj; }

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Challenge 13

Declare a static field.

javascript Your answer 
class Registry {  = 0; }

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Challenge 14

Start a static initialization block.

javascript Your answer 
class Config {  { Config.ready = true; } }

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Challenge 15

Declare a private static field.

javascript Your answer 
class Counter {  = 0; }

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Challenge 16

Declare a static getter.

javascript Your answer 
class Settings {  value() { return 1; } }

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