Manchester | 25-ITP-May | Jennifer Isidienu | Sprint 2 | Data Group

Sprint-2/debug/address.js

@@ -12,4 +12,4 @@ 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

@@ -11,6 +11,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
 }

Sprint-2/debug/recipe.js

@@ -11,5 +11,8 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+  ingredients:`);
+
+for (const ingredient of recipe.ingredients) {
+  console.log(ingredient);
+};

Sprint-2/implement/contains.js

@@ -1,3 +1,6 @@
-function contains() {}
+function contains(obj, prop) {
+  if (typeof obj !== 'object' || obj === null || Array.isArray(obj)) return false;
+  return Object.prototype.hasOwnProperty.call(obj, prop);
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -20,16 +20,27 @@ as the object doesn't contains a key of 'c'
 // 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({}, "a")).toBe(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("contains returns true for existing property", () => {
+  expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
+});
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("contains returns false for non-existent property", () => {
+  expect(contains({ a: 1, b: 2 }, "c")).toBe(false);
+});
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("contains returns false for invalid parameters", () => {
+  expect(contains(3, "a")).toBe(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,15 @@
-function createLookup() {
-  // implementation here
+function createLookup(currencyPairs) {
+  const lookup = {};
+  if (!Array.isArray(currencyPairs)) return lookup;
+
+  for (const pair of currencyPairs) {
+    if (Array.isArray(pair) && pair.length === 2) {
+      const [countryCode, currencyCode] = pair;
+      lookup[countryCode] = currencyCode;
+    }
+  }
+
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,7 +1,14 @@
 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", () => {
+  const input = [['US', 'USD'], ['CA', 'CAD']];
+  const expected = {
+    US: 'USD',
+    CA: 'CAD',
+  };
+
+  expect(createLookup(input)).toEqual(expected);
+}); 
 /*
 
 Create a lookup object of key value pairs from an array of code pairs

Sprint-2/implement/querystring.js

@@ -6,8 +6,10 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    const [key, ...rest] = pair.split("=");
+    const value = rest.join("=");
+    queryParams[decodeURIComponent(key)] = decodeURIComponent(value);
+
   }
 
   return queryParams;

Sprint-2/implement/querystring.test.js

@@ -10,3 +10,14 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+
+test("parses empty querystring", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+test("parses querystring with multiple parameters", () => {
+  expect(parseQueryString("name=Nuel&age=75")).toEqual({
+    "name": "Nuel",
+    "age": "75",
+  });
+  });

Sprint-2/implement/tally.js

@@ -1,3 +1,17 @@
-function tally() {}
+function tally(items) {
+
+  if (!Array.isArray(items)) {
+    throw new Error("Input must be an array");
+  }
+
+  const counts = {};
+
+  for (const item of items) {
+    counts[item] = (counts[item] || 0) + 1;
+  }
+
+  return counts;
+
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -23,12 +23,20 @@ const tally = require("./tally.js");
 // 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("tally on an array with duplicates returns counts for each unique item", () => {
+  expect(tally(['a', 'a', 'b', 'c'])).toEqual({ a: 2, b: 1, c: 1 });
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("tally on invalid input throws an error", () => {
+  expect(() => tally("invalid")).toThrow("Input must be an array");
+});

Sprint-2/interpret/invert.js

@@ -17,13 +17,33 @@ function invert(obj) {
 }
 
 // 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?
+// Object.entries returns an array of key-value pairs from the object.
+// Eg { a: 1, b: 2 }, it returns [['a', 1], ['b', 2]].
+// It is needed to iterate over the object's properties 
+// in a way that allows us to access both keys and values simultaneously.
 
 // d) Explain why the current return value is different from the target output
+// It incorrectly assigns value to key property of invertedObj,
+// instead of using the key as a property name and value as its value.
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+function invert(obj) {
+  const invertedObj = {};
+
+  for (const [key, value] of Object.entries(obj)) {
+    invertedObj[value] = key;
+  }
+
+  return invertedObj;
+}
+console.log(invert({ a: 1 }));
+console.log(invert({ a: 1, b: 2 }));