London | 26-ITP-Sep | Mahir Shah | Sprint 2 | Sprint 2 coursework

Sprint-2/debug/address.js

@@ -1,4 +1,8 @@
 // Predict and explain first...
+// This will print My house number is undefined
+// Because the template literal tries to access the number like it is an array,
+// But this is incorrect as it is an object which uses a different way to access 
+// elements
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
@@ -12,4 +16,4 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(`My house number is ${address.houseNumber}`);

Sprint-2/debug/author.js

@@ -1,7 +1,9 @@
 // Predict and explain first...
+// Throw error because I don't think for of works like that for objects
 
 // This program attempts to log out all the property values in the object.
 // But it isn't working. Explain why first and then fix the problem
+// Doesn't work because author isn't an iterable, so it can't be looped over
 
 const author = {
   firstName: "Zadie",
@@ -11,6 +13,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
-  console.log(value);
+for (const [key, value] of Object.entries(author)) {
+  console.log(`${key}: ${value}`);
 }

Sprint-2/debug/recipe.js

@@ -1,5 +1,6 @@
 // Predict and explain first...
-
+// This will print "bruschetta serves 2
+//  ingredients: " Then not sure, but definitely not the ingredients
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
 // How can you fix it?
@@ -11,5 +12,4 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+  ingredients:\n\t${recipe.ingredients.join("\n\t")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,17 @@
-function contains() {}
+function checkIfObj(objToCheck) {
+  if (
+    typeof objToCheck !== "object" ||
+    objToCheck === null ||
+    (Object.getPrototypeOf(objToCheck) !== Object.prototype &&
+      Object.getPrototypeOf(objToCheck) !== null)
+  ) {
+    throw new Error("contains requires an object");
+  }
+}
+
+function contains(objToCheck, keyToSearch) {
+  checkIfObj(objToCheck);
+  return Object.keys(objToCheck).includes(keyToSearch);
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -23,18 +23,31 @@ as an array isn't an object
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
+test("contains on empty object returns false", () => {
+  expect(contains({})).toEqual(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
-// Then it should return true
+// Then it should return true#
+test("given object with properties, and wanted property exists, returns true", () => {
+  expect(contains({ a: 1, b: 2 }, "a")).toEqual(true);
+});
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("given object with properties, and wanted property doesn't exist, returns false", () => {
+  expect(contains({ a: 1, b: 2 }, "c")).toEqual(false);
+});
 
 // Given a value that isn't an object - an array, a string, a number,
 // null, or no argument at all
 // When passed to contains
 // Then it should throw Error("contains requires an object")
 // (careful: typeof [] and typeof null are both "object")
+test("given something that isn't an object, throw error", () => {
+  expect(() => contains([1,2,5])).toThrow(
+    Error("contains requires an object")
+  );
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,11 @@
-function createLookup() {
-  // implementation here
+function createLookup(countryCurrencyPairs) {
+  const objCountryCurrencyPairs = {};
+
+  for (const pair of countryCurrencyPairs) {
+    objCountryCurrencyPairs[pair[0]] = pair[1];
+  }
+
+  return objCountryCurrencyPairs;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,16 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
+test("creates a country currency code lookup for multiple codes", () => {
+  expect(
+    createLookup([
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ])
+  ).toEqual({
+    US: "USD",
+    CA: "CAD",
+  });
+});
 
 /*
 

Sprint-2/implement/querystring.js

@@ -6,10 +6,33 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
-  }
+    if (pair === "") {
+      continue;
+    }
+
+    if (!pair.includes("=")) {
+      const key = decodeURIComponent(pair).replace("+", " ");
+      queryParams[key] = "";
+    } else {
+      const key = decodeURIComponent(pair.slice(0, pair.indexOf("="))).replace(
+        "+",
+        " "
+      );
+      const value = decodeURIComponent(
+        pair.slice(pair.indexOf("=") + 1)
+      ).replace("+", " ");
 
+      if (Object.keys(queryParams).includes(key)) {
+        if (Array.isArray(queryParams[key])) {
+          queryParams[key].push(value);
+        } else {
+          queryParams[key] = [queryParams[key], value];
+        }
+      } else {
+        queryParams[key] = value;
+      }
+    }
+  }
   return queryParams;
 }
 

Sprint-2/implement/tally.js

@@ -1,3 +1,16 @@
-function tally() {}
+function tally(itemList) {
+  if (!Array.isArray(itemList)) {
+    throw new Error("tally requires an array");
+  }
+  const talliedItems = {};
+  for (const item of itemList) {
+    if (!Object.keys(talliedItems).includes(item)) {
+      talliedItems[item] = 1;
+    } else {
+      talliedItems[item] += 1;
+    }
+  }
+  return talliedItems;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -19,16 +19,32 @@ const tally = require("./tally.js");
 // Given a function called tally
 // When passed an array of items
 // Then it should return an object containing the count for each unique item
+test("Given an array of items, return object contain count for each unique item", () => {
+  expect(tally(["a", "a", "b", "c"])).toEqual({ a: 2, b: 1, c: 1 });
+});
 
 // Given an empty array
 // When passed to tally
 // Then it should return an empty object
-test.todo("tally on an empty array returns an empty object");
+test("tally on an empty array returns an empty object", () => {
+  expect(tally([])).toEqual({});
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("Given an array of items with duplicates, return object contain count for each unique item", () => {
+  expect(tally(["a", "a", "b", "c", "d", "b", "a"])).toEqual({
+    a: 3,
+    b: 2,
+    c: 1,
+    d: 1,
+  });
+});
 
 // Given an invalid input like a string, a number, or no argument at all
 // When passed to tally
 // Then it should throw Error("tally requires an array")
+test("Given something that is not an array, throws error", () => {
+  expect(() => tally("Not an array")).toThrow(Error("tally requires an array"));
+});

Sprint-2/interpret/invert.js

@@ -10,20 +10,29 @@ function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
+module.exports = invert;
+
 // a) What is the current return value when invert is called with { a : 1 }
+// {key: 1}
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// {key: 2}
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// {"1": "a", "2":"b"}
 
 // c) What does Object.entries return? Why is it needed in this program?
+// An array of the objects key-value pairs. Used here so we can for loop over all key-value pairs in the object
 
 // d) Explain why the current return value is different from the target output
+// because the key is a variable, bracket notations has to be used. with .notation it uses the word, not the variable so in this case the
+// key is the word 'key'. Also the key and value are the wrong way round, the key of the original object is being given the value of the
+// original object, essentially doing nothing
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,5 @@
+const invert = require("./invert.js");
+
+test("Given object, returns object with inverted values and keys", () => {
+  expect(invert({ a: 8, b: 2 })).toEqual({ 8: "a", 2: "b" });
+});