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JavaScript Design Patterns for Coding Interviews

Challenge: Solution Review

This lesson will explain the solution to the problem from the previous coding challenge.

We'll cover the following...

Solution #

Node.js
class Dress{
  constructor(serialNumber,type,color,designer,availability){
    this.serialNumber = serialNumber
    this.type = type
    this.color = color
    this.designer = designer
    this.availability = availability
    this.price = 0
  }
  dressPrice(){
    if(this.type == "maxi"){
      this.price = 1000
    }
    if(this.type == "gown"){
      this.price = 2000
    }
    if(this.type = "skirt"){
      this.price = 500
    }
    return this.price
  }  
}
class DressFactory {
  constructor() {
    this.existingDresses = {}
  }
  createDress(serialNumber,type,color, designer, availability) {
    var exists = this.existingDresses[serialNumber]
  
    if (!!exists) {
      return this.existingDresses[serialNumber]
    }
    else {
        var dress = new Dress(serialNumber,type,color, designer, availability)
        this.existingDresses[serialNumber]= dress
        return dress
      }
    }
}
const factory = new DressFactory()
const pinkdress1 = factory.createDress("#123","skirt","pink","Zara","yes")
const pinkdress2 = factory.createDress("#123","skirt","pink","Zara","yes")
console.log(pinkdress1 === pinkdress2)
console.log(pinkdress1.dressPrice())
console.log(pinkdress2.dressPrice())

Explanation

As explained in the problem statement, we need to implement a functionality that doesn’t allow dresses with the same serialNumber to be made more than once. For this purpose, a flyweight factory can be used. Before we get into that, let’s look into the Dress class first.

class Dress{
  constructor(serialNumber,type,color,designer,availability){
    this.serialNumber = serialNumber
    this.type = type
    this.color = color
    this.designer = designer
    this.availability = availability
    this.price = 0
  }
...