eFarmony Data Structures: Objects as Data Models

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In this section we will explore how to represent our eFarmony data as a JavaScript object.

You will be placing all your code into the scripts.js file.

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###Animal User Model

This object will be the model of a single animal user. Extra points if you get the pun in the last sentence.

Object

An object to hold our data model...

• Create a variable, name it animal, and assign it an object literal.

With Dot Notation…

• Add a property called username and assign it a value.
• Ensure that your username property exists in animal by inspecting it in the console.

With Bracket Notation…

• Add a property called tagline and give it a value.
• Check that your property exists in the animal object by inspecting it in the console.
• Create a variable called noises and assign it an empty array []
• Add the noises array to your object.
• Inspect your handiwork! Your object should look something like this:

  { username: 'DaffyDuck', tagline: 'Yippeee!', noises: [] }

Loops

• Loop through the properties of your animal object.
• Count everytime it loops to keep track of the number of properties on your object.
• Write an if/else statement in your loop:
  • If the key is username, console.log('Hi my name is ' + ___) //fill in with object's username value.
  • If the key is tagline, console.log('I like to say ' + ___) //fill in with object's tagline value.
• What happens if you return 'Hi my name is ' + ___ instead of using console.log() inside the loop?

Review

Let's go over some concepts:

• What are the different ways you can add properties and values to objects?
• Which of these methods would you use if you wanted to add a property to an object that had a weird symbol (think '&')?
• What about if the property is a variable, how does that change the syntax?

//Functions exercises

Part 2: eFarmony Functions

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You will be placing all your code into the scripts.js file

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Animal User

1. Write a function, AnimalTestUser, that has one string parameter, username. It returns an object with a username property.

var testSheep = AnimalTestUser('CottonBall');
console.log(testSheep); //{ username: 'CottonBall' }

1. In your AnimalTestUser function, create a check that sees how many arguments are passed. If there is more than one argument, create a property, otherArgs that is an array of the remaining arguments. Note: the arguments keyword is not a true array. Remember, it is an array-like object.

var testSheep = AnimalTestUser('CottonBall', {'loves dancing': true}, [1,2,3] );
console.log(testSheep); //{ username: 'CottonBall', otherArgs: [ {'loves dancing': true}, [1,2,3] ] }

1. Write a constructor function, AnimalCreator that returns a single animal object. The constructor function has 4 parameters: username, species, tagline, and noises. The animal object should have at least 5 properties: username, species, noises, tagline, and friends. The values should all be strings except noises and friends, which are arrays.

var sheep = AnimalCreator('Cloud', 'sheep', 'You can count on me!', ['baahhh', 'arrgg', 'chewchewchew']);
console.log(sheep);
      // { username: 'Cloud', 
      //  species: 'sheep', 
      //  tagline: 'You can count on me!', 
      //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
      //  friends: []
      // }

1. Write a function, addFriend that takes an animal object (like the one returned from the AnimalCreator function) and adds another animal object as a friend.

  addFriend(sheep, cow);
  console.log(sheep);
        // { username: 'Cloud', 
        //  species: 'sheep', 
        //  tagline: 'You can count on me!', 
        //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
        //  friends: [{username: 'Moo', species: 'cow'...}]
        // }
  addFriend(sheep, llama);
  console.log(sheep);
        // { username: 'Cloud', 
        //  species: 'sheep', 
        //  tagline: 'You can count on me!', 
        //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
        //  friends: [{username: 'Moo', species: 'cow'...}, {username: 'Zeny', species: 'llama'...}]
        // }

1. Change your addFriend function to only add the username of the friend, not the whole object.

  addFriend(sheep, cow);
  console.log(sheep);
        // { username: 'Cloud', 
        //  species: 'sheep', 
        //  tagline: 'You can count on me!', 
        //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
        //  friends: ['Moo']
        // }
  addFriend(sheep, llama);
  console.log(sheep);
        // { username: 'Cloud', 
        //  species: 'sheep', 
        //  tagline: 'You can count on me!', 
        //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
        //  friends: ['Moo', 'Zeny']
        // }

1. Create a myFarm collection of at least 3 animal objects. Give them some friends using addFriend, too!

console.log(myFarm) //[{username: 'Cloud'...},{username: 'Zeny'...},{username: 'CottonBall'...}]

1. Create a function, addMatchesArray, that takes a farm (array of animal objects) and adds a new property to each animal object called matches that is an empty array. Hint: you will need a loop.

addMatchesArray(myFarm); 
console.log(myFarm[0]); // { username: 'Cloud', 
        //  species: 'sheep', 
        //  tagline: 'You can count on me!', 
        //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
        //  friends: ['Moo', 'Zeny'],
        //  matches: []
        // }

1. Create a function, giveMatches, that takes a farm collection (aka an array of animal objects) that already has a matches property. It selects a name from the friends array and adds it to the matches array. You can choose how the selection is made (random, the first element, etc). Make sure all your animal objects have friends.

giveMatches(myFarm); 
console.log(myFarm[0]); // { username: 'Cloud', 
        //  species: 'sheep', 
        //  tagline: 'You can count on me!', 
        //  noises: ['baahhh', 'arrgg', 'chewchewchew'], 
        //  friends: ['Moo', 'Zeny'],
        //  matches: ['Zeny']
        // }