The ultimate guide to coding interviews: Learn and practice JavaScript design patterns tested by FAANG engineers. Get interview-ready in just a few hours with battle-tested solutions.

If you're an experienced developer, chances are your interviewer won't ask you about language syntax. Instead, they'll focus on things that test your understanding of software architecture, and how capable you are at finding optimized solutions to given problems. 

That’s where a strong understanding of design patterns comes in handy. It's often useful to be able to draw on established patterns instead of reinventing the wheel.

In this course, you will learn how to effectively deploy design patterns to answer interview questions. The course is divided into four sections: Creational Patterns, Structural Patterns, Behavioral Patterns, and Architectural Patterns. Each section has its own set of design patterns which you’ll learn to use through various challenges. 

Every challenge contains a detailed solution explanation. By the end of this course (and with some practice), you will be able to confidently use design patterns to tackle advanced coding interview questions in JavaScript.

JavaScript Design Patterns for Coding Interviews

# Problem statement

In this challenge, you are given a `TruthAndDare` program like this: 



// old interface
class TruthAndDare {
  constructor(){
    this.turn = Math.floor(Math.random() * 2) + 1;
  }
  Getturn(){
    if(this.turn == 1){
      this.turn = 2
    }else{
      this.turn = 1
    }
    return this.turn
  }
  playGame(playerOnename,playerTwoname){
    if(this.Getturn() == 1){
      return`${playerOnename}'s turn`
    }else{
      return `${playerTwoname}'s turn`
    }
  }
}

const obj = new TruthAndDare()
console.log(obj.playGame("Ross","Chandler"))

There is a variable `turn` that decides which player's turn it is to give a dare or ask a question. The `Getturn()` function is used to set and return the `turn`. It is set to either 1 or 2. The `playGame` function is simple: it takes two players and depending on the value of `turn`, returns the name of the player whose turn it is. 

Now, as the creator of the game, you want to update the game. You want the turns to be random such that they are not limited to the values 1 or 2. So here's what you want to change:


* The `turn` value to be a random number. In the `playGame` function, if the `turn` is an even number, it'll be player 1's turn else it'll be player 2's turn. You name the updated function, `newPlayGame`.


Make a new interface for the updated functionality like so: 

In this challenge, you have to implement the adapter pattern to solve the given problem.

Before We Begin

Introduction To Design Patterns

Creational Patterns

Structural Patterns

Behavioral Patterns

Architectural Patterns

Conclusion

Challenge: Adapter Pattern

Problem statement