Challenge: Observer Pattern

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

We'll cover the following

Problem statement

In this challenge, you have to implement an Auction system using the observer pattern.

You have two classes Auctioneer (the person conducting the bid) and Bidder (the bidder bidding for the object).

Here’s what the Auctioneer class needs to do:

  • It should maintain a list of all bidders.

  • It should have a function registerBidder to register the bidders.

  • It should have an announceNewBidderPrice function to announce the bidding price given by a bidder.

  • It should have a notifyBidders function to notify each bidder of the new bidding price.

Bidder should have the following:

  • A name and bidPrice.

  • An update function that displays the name of the bidder along with the bidPrice they are giving. For example, {insert name} is offering {insert bid price} dollars. It should display Sold to {insert name of bidder here} if the bid price exceeds 500 dollars.

  • A giveNewPrice function that sets the bid price of a bidder.

Input

The announceNewBidderPrice function is called after different bidders have given their prices

Output

The name of the bidders and the prices they gave are displayed along with the name of the bidder who wins the bid

Sample input

auctioner = new Auctioneer();
bidder1 = new Bidder("Ross");
auctioner.registerBidder(bidder1);
bidder2 = new Bidder("Joey");
auctioner.registerBidder(bidder2);
bidder1.giveNewPrice(400);
bidder2.giveNewPrice(550);
auctioner.announceNewBidderPrice()

Sample output

"Ross is offering 400 dollars"
"Joey is offering 550 dollars"
"Sold to Joey"

Challenge #

Take a close look and design a step-by-step solution before jumping on to the implementation. This problem is designed for your practice, so try to solve it on your own first. If you get stuck, you can always refer to the solution provided. Good Luck!

class Auctioneer
{
    constructor(){
        //define constructor here
    }
    //write code here
}
class Bidder 
{
    constructor(){
        //define constructor here
    }
    //write code here  
}

Let’s discuss the solution in the next lesson.