Homework

src/HOF/problem1.js

@@ -1,5 +1,12 @@
 
 function callNoException(f, arg) {
+
+    try {
+        return f(arg);
+    }
+    catch(err) {
+        return null;
+    }
     // if f(arg) throws an exception, return null
     // otherwise return what f(arg) returned
     // Example:
@@ -12,6 +19,10 @@ function callNoException(f, arg) {
 }
 
 function callNoNull(f, arg) {
+    if (f(arg) == null) {
+        throw new Error("f(arg) is not null");
+    }
+    return f(arg);
     // if f(arg) returns null, throw an exception
     // otherwise return what f(arg) returned  
     // Example: 
@@ -26,6 +37,15 @@ function callNoNull(f, arg) {
 }
 
 function exceptionalize(f) {
+
+    var k = function(arg){
+        if (f(arg) == null) {
+            throw new Error("f(arg) is null")
+        }
+        return f(arg);
+    }
+    return k;
+
     // returns a new function
     // this function takes 1 input, called arg
     // if f(arg) is null, this new function throws an exception
@@ -43,6 +63,16 @@ function exceptionalize(f) {
 }
 
 function nullify(f) {
+
+    var k = function(arg) {
+        try {
+            return f(arg);
+        }
+        catch(err) {
+            return null;
+        }
+    }
+    return k;
     // returns a new function
     // this function takes 1 input, called arg
     // if f(arg) throws an exception, this new function returns null
@@ -59,6 +89,14 @@ function nullify(f) {
 }
 
 function map(lst, f) {
+
+    var arr = [];
+
+    for (var i = 0; i < lst.length; i++) {
+        arr.push(f(lst[i]));
+    }
+
+    return arr;
     // lst is an array and f is a function
     // map returns an array with the same number of elements as lst
     // if lst = [a1, a2, a3, a4, a5] then map(lst, f) returns [f(a1), f(a2), f(a3), f(a4), f(a5)]
@@ -72,6 +110,15 @@ function map(lst, f) {
 }
 
 function filter(lst, f) {
+    var arr = [];
+
+    for (var i = 0; i < lst.length; i++) {
+        if (f(lst[i])) {
+            arr.push(lst[i])
+        }
+    }
+
+    return arr;
     // lst is an array and f is a function
     // f takes one argument and returns a boolean (true or false)
     // filter(lst, f) returns a list with all the elements of lst that does not satisfy f removed
@@ -86,6 +133,16 @@ function filter(lst, f) {
 }
 
 function every(lst, f) {
+
+    var out = true;
+
+    for (var i = 0; i < lst.length; i++) {
+        if (f(lst[i]) == false) {
+            var out = false;
+        }
+    }
+
+    return out;
     // lst is an array and f is a function
     // f takes 1 arguments and returns a boolean
     // filter(lst, f) returns a true if f returns true for every element of lst

src/__proto__/problem1.js

@@ -3,4 +3,6 @@
 var parent = {x: 5, y: 6, z: 8};
 var child = {x : 10};
 
+child.__proto__ = parent;
+
 module.exports = {parent, child}

src/anonymous-functions/problem1.js

@@ -1,12 +1,13 @@
 // fix all the errors
+
 function c(g, h) {
     var x = g(6);
     var y = h(8);
     return [x, y];
 }
 
 function t() {
-    return c(function g(x) {return y + 1}, function h(y) {return x * 2});
+    return c(function(x) {return x + 1}, function(y) {return y * 2});
 }
 
-module.exports = t;
+module.exports = t;

src/arrow-functions/problem1.js

@@ -6,7 +6,7 @@ function c(g, h) {
 }
 
 function t() {
-    return c( x => return y + 2, (x,y) => return x + y);
+    return c( x => x + 2, (x,y) => x + y);
 }
 
 module.exports = t

src/arrow-functions/problem2.js

@@ -1,9 +1,17 @@
 // Convert all the arrow functions to normal anonymous functions
 // There should be no arrows by the end
 
-var x = x => x + 1;
-var y = (x, y) => x + y;
-var z = x => {var y = (x * 7) % 2; return y * 2};
+var x = function(x) {
+    return x + 1;
+}
+
+var y = function(x, y) {
+    return x + y;
+}
+
+var z = function(x){
+    var y = (x * 7) % 2; return y * 2
+}
 
 module.exports = {x, y, z};
 

src/bind/problem1.js

@@ -1,7 +1,12 @@
 var bob = {name: "Bob"};
+
 function greet() {
     return "I'm " + this.name;
 }
+
+ var greet = greet.bind(bob);
+
+
 // bind greet to bob
 
 module.exports = greet;

src/bind/problem2.js

@@ -1,9 +1,9 @@
 // Fix all the errors in this program
 var dog = {breed: "schnitzel"};
 function greet() {
-    return "I'm a " + this.bred;
+    return "I'm a " + this.breed;
 }
 
-greet.bind(dog);
+var greet = greet.bind(dog);
 
 module.exports = greet;

src/callbacks/problem1.js

@@ -1,7 +1,17 @@
 // Fix all the errors. It should print hello after 1 second
 
-function shout(x) {
+function shoutLoudly(x) {
+    console.log(x.toUpperCase())
+}
+
+function shout() {
+    return shoutLoudly("hello");
+}
+
+setTimeout(shout, 1000);
+
+/* function shout(x) {
     console.log(x.toUppercase());
 }
 
-SetTimeout(shout("hello"), 1);
+SetTimeout(shout("hello"), 1); */

src/classes/problem1.js

@@ -1,4 +1,10 @@
 class Dog {
+    constructor(age, name, breed) {
+        this.age = age;
+        this.name = name;
+        this.breed = breed;
+        this.bark = () => "woof";
+    }
     // Dog has a constructor with three arguments (in this order): age, name and breed
     // Dog has three attributes: age, name and breed
     // Dog has a method bark, which returns a string    

src/constructor-functions/problem1.js

@@ -1,2 +1,4 @@
 // Add a function to all arrays called isNotEmpty
 // isNotEmpty returns true is the array is empty, false otherwise
+
+Array.prototype.isNotEmpty = function(){return this.length != 0};

src/exceptions/problem1.js

@@ -1,20 +1,36 @@
 function first(arr) {
-    // Throw an exception if the array has no elements
-    // Otherwise return the first element
+    if (arr.length == 0) {
+        throw new Error("No elements");
+    } else {
+        return arr[0];
+    }
+
 }
 
 function detective(i) {
     function suspect(i) {
         if(i * 7 % 3 == 0) throw new Error("Bad i!");
     }
-    // detective checks to see if the suspect throws an exception on input i.
-    // Returns "everything ok" if the suspect doesn't. 
-    // Returns "something fishy" if the suspect does.
+
+    try {
+        suspect(i) 
+        return "everything ok";
+    }
+    catch(e) {
+        return "something fishy";
+    }
 }
 
 function assignFlight(name) {
     var flightNumber = ((name.length * 7) % 20) + "0";
     var terrorSuspects = ["bob", "eric", "susie"];
+
+    for (var i = 0; i < terrorSuspects.length; i++) {
+        if (name == terrorSuspects[i]) {
+            throw new Error("Terrorist!");
+        }
+        return flightNumber;
+    }
     // if the name is a terror suspect, throw an exception
     // Otherwise, return the flight number
 }

src/inheritance/problem1.js

@@ -4,7 +4,20 @@ class Shape {
     }
 }
 
-class Rectangle {
+class Rectangle extends Shape {
+    constructor(width, height) {
+        super();
+        this.width = width;
+        this.height = height;
+    }
+
+    area() {
+        return this.width * this.height;
+    }
+
+    perimeter() {
+        return (this.width * 2) + (this.height * 2);
+    }
 
     // A rectangle is a shape
     // Every rectangle has a width and a height
@@ -13,7 +26,12 @@ class Rectangle {
     // The constructor has two arguments: width and height
 }
 
-class Square {
+class Square extends Rectangle{
+    constructor(size) {
+        super();
+        this.width = size;
+        this.height = size;
+    }
     // A square is a rectangle
     // Every square has a width and a height
     // The height and width of a square are always the same

src/inheritance/problem2.js

@@ -2,24 +2,24 @@
 
 class Shape {
     constructor(shapeName) {
-        this.shapName = shapeName;
+        this.shapeName = shapeName;
     }
     toString() {
         return this.shapeName + " with area " +
-          this.area() + " and perimeter " + this.permeter();
+          this.area() + " and perimeter " + this.perimeter();
     }
 }
 
-class Square {
+class Square extends Shape {
     constructor(size) {
-        supr("square");
+        super("square");
         this.size = size;
     }
     area() {
-        return this.size * this.siz;
+        return this.size * this.size;
     }
     perimeter() {
-       return this.size * 4;
+        return this.size * 4;
     }
 }
 

src/return/problem1.js

@@ -1,17 +1,11 @@
-// Remove as many characters from this function without changing its meaning.
-// In other words, make this function as succinct as possible
-// Also, remove these comments
-
 function f(x) {
     if(x > 10) {
         return "hello";
     } else if(x > 5) {
         return "goodbye";
-    } else {
-        return undefined;
     }
 }
 
-module.exports = f; // Don't delete this line but remove this comment.
+module.exports = f;
 
 

src/this/problem1.js

@@ -1,5 +1,11 @@
 'use strict';
 function whatsMyAgeAgain() {
+    try {
+        return this.age;
+    }
+    catch(e) {
+        return 18;
+    }
     // returns this.age unless this is not defined. If this is not defined, return 18
 }
 

src/variable-scoping/problem1.js

@@ -2,9 +2,9 @@
 // It should return a different number every time it is called
 // The first time it is called it returns 1
 // Every call thereafter returns a number one greater than the last
+var x = 0;  
 
 function f() {
-    var x = 0;  
     x = x + 1;
     return x;
 }