Finished homework #3

Feynman Writing Prompts.txt

@@ -0,0 +1,25 @@
+
+    Objects
+
+	Objects encapsulate data and functions together. They can contain many data members and also function members.
+	You access each function and data member by their name.
+
+    Properties
+
+	The properties of an object are the data that an object encapsulates. They are the objects variables.
+
+    Methods
+
+	The methods of an object are the functions that an object encapsulates. They are the object's member
+	functions.
+
+    for in loop
+
+	The for in loop is like iterating over all the properties of an object. You can execute some piece of code
+	for each property of an object.
+
+    Dot notation vs bracket notation
+
+	Bracket notation and dot notation are two different ways to access the properties of an object. Bracket
+	notation is needed when properties of an object do not have a valid variable name. If
+	the variable name is good, then you can use dot notation.

exercises.js

@@ -5,68 +5,105 @@ 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 cat = {
+    name: name,
+    age: age,
+    meow: function() {
+      return 'Meow!';
+    }
+  };
+  return cat;
 }
 
 function addProperty(object, property) {
   // 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)
+  object[property] = null;
+  return object;
 }
 
 function invokeMethod(object, method) {
   // method is a string that contains the name of a method on the object
   // invoke this method
   // nothing needs to be returned
+  object[method]();
 }
 
 function multiplyMysteryNumberByFive(mysteryNumberObject) {
   // mysteryNumberObject has a property called mysteryNumber
   // multiply the mysteryNumber property by 5 and return the product
+  return mysteryNumberObject.mysteryNumber * 5;
 }
 
 function deleteProperty(object, property) {
   // remove the property from the object
   // return the object
+  delete object[property];
+  return object;
 }
 
 function newUser(name, email, password) {
   // create a new object with properties matching the arguments passed in.
   // return the new object
+  return {
+    name: name,
+    email: email,
+    password: password
+  };
 }
 
 function hasEmail(user) {
   // return true if the user has a value for the property 'email'
   // otherwise return false
+  if (!user.hasOwnProperty('email')) {
+    return false;
+  }
+  if (user.email != '') {
+    return true;
+  } else {
+    return false;
+  }
 }
 
 function hasProperty(object, property) {
   // return true if the object has the value of the property argument
   // property is a string
   // otherwise return false
+  return object.hasOwnProperty(property);
 }
 
 function verifyPassword(user, password) {
   // check to see if the provided password matches the password property on the user object
   // return true if they match
   // otherwise return false
+  return user.password === password;
 }
 
 function updatePassword(user, newPassword) {
   // replace the existing password on the user object with the value of newPassword
   // return the object
+  user.password = newPassword;
+  return user;
 }
 
 function addFriend(user, newFriend) {
   // user has a property called friends that is an array
   // add newFriend to the end of the friends array
   // return the user object
+  user.friends.push(newFriend);
+  return user;
 }
 
 function setUsersToPremium(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
+  for (var i = 0; i < users.length; i++) {
+    users[i].isPremium = true;
+  }
+  return users;
 }
 
 function sumUserPostLikes(user) {
@@ -75,6 +112,11 @@ function sumUserPostLikes(user) {
   // each post object has an integer property called 'likes'
   // sum together the likes from all the post objects
   // return the sum
+  var sum = 0;
+  user.posts.forEach(function sumLikes(elem) {
+    sum += elem.likes;
+  });
+  return sum;
 }
 
 function addCalculateDiscountPriceMethod(storeItem) {
@@ -85,6 +127,11 @@ function addCalculateDiscountPriceMethod(storeItem) {
   // price -> 20
   // discountPercentage -> .2
   // discountPrice = 20 - (20 * .2)
+  storeItem.calculateDiscountPrice = function() {
+    var discount = this.price * this.discountPercentage;
+    return this.price - discount;
+  };
+  return storeItem;
 }
 
 // Do not modify code below this line.