Homework 3

Explanations.txt

@@ -0,0 +1,33 @@
+Objects: Objects are a way to hold and categorize information. They are a way
+to collect properties. Each property can either be an association between a key
+and a value, or a method.
+
+----------------------------------------------------------
+
+Properties: A property is a way to describe something. For example, if you have a
+"car" object, you may want to have a property that describes the car's color or how
+many doors it has. Also, you may have another property that describes something the
+car does. For example, you could have a function that describes the sequence of events
+as the car is started (car.pressBrake(), car.turnKey(), car.startEngine()). 
+
+----------------------------------------------------------
+
+Methods: A method is an action (or a collection of actions) grouped under a single function
+to complete a task. For example, you could have a method called sum() that takes two parameters and
+adds them.
+
+----------------------------------------------------------
+
+for in loop: A for in loop is a way to iterate over values and perform an action. You could
+iterate over array values and add five to each odd number, or iterate over each property in
+an object. It is a very versatile way to efficiently perform a large action set without
+using verbose language.
+
+
+----------------------------------------------------------
+
+dot notation vs bracket notation: In some cases, dot notation and bracket notation are
+equivalent, such as using console.log vs console[log]. When a variable is unknown, such as
+on a webpage where a user interacts by entering variables into the field linked to a method,
+it is often better to use bracket notation because it will consider the value, as opposed to
+the literal string entered.

exercises.js

@@ -7,71 +7,121 @@ function makeCat(name, age) {
   //add an age property to the object with the value set to the age argument
   //add a method called meow that returns the string 'Meow!'
   //return the object
+
+    var newCat = {
+
+    name: name,
+    age: age,
+    meow: function () {
+      return 'Meow!';
+    }
+  };
+return newCat;
 }
 
 function addProperty(object, property) {
+  object[property] = null;
+  return object;
   //add the property to the object with a value of null
   //return the object
   //note: the property name is NOT 'property'.  The name is the value of the argument called property (a string)
 }
 
 function invokeMethod(object, method) {
+  object[method]();
+
   //method is a string that contains the name of a method on the object
   //invoke this method
   //nothing needs to be returned
 }
 
 function multiplyMysteryNumberByFive(mysteryNumberObject) {
+  return mysteryNumberObject['mysteryNumber'] * 5;
   //mysteryNumberObject has a property called mysteryNumber
   //multiply the mysteryNumber property by 5 and return the product
 }
 
 function deleteProperty(object, property) {
+  delete object[property];
+  return object;
   //remove the property from the object
   //return the object
 }
 
 function newUser(name, email, password) {
+  var newObject = {
+    name: name,
+    email: email,
+    password: password
+  };
+  return newObject;
   //create a new object with properties matching the arguments passed in.
   //return the new object
 }
 
 function hasEmail(user) {
+  if (user.email !== undefined && user.email.length > 0) {
+  return true;
+  }
+  return false;
   //return true if the user has a value for the property 'email'
   //otherwise return false
 }
 
 function hasProperty(object, property) {
+  if (object[property] !== undefined) {
+    return true;
+  } return false;
   //return true if the object has the value of the property argument
   //property is a string
   //otherwise return false
 }
 
 function verifyPassword(user, password) {
+  if (password === user.password) {
+    return true;
+  }
+  return false;
   //check to see if the provided password matches the password property on the user object
   //return true if they match
   //otherwise return false
 }
 
 function updatePassword(user, newPassword) {
+  user.password = newPassword;
+  return user;
   //replace the existing password on the user object with the value of newPassword
   //return the object
 }
 
 function addFriend(user, newFriend) {
+  user.friends.push(newFriend);
+  return user;
   //user has a property called friends that is an array
   //add newFriend to the end of the friends array
   //return the user object
 }
 
 function setUsersToPremium(users) {
+  for (var i = 0; i < users.length; i++) {
+    users[i].isPremium = true; 
+  }
+  return users;
   //users is an array of user objects.
   //each user object has the property 'isPremium'
   //set each user's isPremium property to true
   //return the users array
 }
 
 function sumUserPostLikes(user) {
+
+  var sum = 0;
+   var userPosts = user.posts; 
+   for (var i = 0; i < userPosts.length; i++) {
+     sum += userPosts[i].likes;
+   } 
+   return sum;
+
   //user has an array property called 'posts'
   //posts is an array of post objects
   //each post object has an integer property called 'likes'
@@ -80,6 +130,12 @@ function sumUserPostLikes(user) {
 }
 
 function addCalculateDiscountPriceMethod(storeItem) {
+
+  storeItem.calculateDiscountPrice = function() {
+    var discount = this.price - (this.price * this.discountPercentage);
+    return discount;
+  };
+  return storeItem;
   //add a method to the storeItem object called 'calculateDiscountPrice'
   //this method should multiply the storeItem's 'price' and 'discountPercentage' to get the discount
   //the method then subtracts the discount from the price and returns the discounted price