Sheffield | 26-ITP-Jan | Karim M'hamdi | Sprint 2 | Module-Data-Groups

Sprint-2/debug/address.js

@@ -1,4 +1,7 @@
 // Predict and explain first...
+//if you run this code with console.log('My house number is ${address[0]}'); it well log out 'My house number is undefined' becouse adress is an object and not an array.
+// to fix this we need to remove (`My house number is ${address[0]}`); and chnage it to (adress.houseNumber) becouse we need to access the houseNumber property of the address object.
+// Then it well log out 42 as expected.
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
@@ -12,4 +15,4 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(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

@@ -10,6 +10,8 @@ const recipe = {
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+console.log(recipe.title);
+console.log(`Serves: ${recipe.serves}`);
+console.log("Ingredients:");
+console.log(recipe.ingredients.join("\n"));
+

Sprint-2/implement/contains.js

@@ -1,3 +1,13 @@
-function contains() {}
+function contains(obj, prop) {
+  if (typeof obj !== "object" || obj === null) {
+    return false;
+  }
+
+  if (Array.isArray(obj)) {
+    return false;
+  }
+  return obj.hasOwnProperty(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 an empty object returns false", function () {
+  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 when property exists", function () {
+  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 when property does not exist", function () {
+  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 when passed an array", function () {
+  expect(contains([1, 2, 3], "0")).toBe(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,10 @@
-function createLookup() {
-  // implementation here
+function createLookup(countryCurrencyPairs) {
+  const lookup = {};
+
+  for (const pair of countryCurrencyPairs) {
+       lookup[pair[0]] = pair[1];
+  }
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,9 @@
 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", function() {
+  expect(createLookup([['US', 'USD'], ['CA', 'CAD']])).toEqual({'US': 'USD', 'CA': 'CAD'});
+});
+
 
 /*
 

Sprint-2/implement/querystring.js

@@ -1,12 +1,19 @@
 function parseQueryString(queryString) {
   const queryParams = {};
+
   if (queryString.length === 0) {
     return queryParams;
   }
+
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    if (!pair) continue;
+
+    const firstEqualsIndex = pair.indexOf("=");
+    const key = pair.slice(0, firstEqualsIndex);
+    const value = pair.slice(firstEqualsIndex + 1);
+
     queryParams[key] = value;
   }
 

Sprint-2/implement/querystring.test.js

@@ -8,5 +8,23 @@ const parseQueryString = require("./querystring.js")
 test("parses querystring values containing =", () => {
   expect(parseQueryString("equation=x=y+1")).toEqual({
     "equation": "x=y+1",
+
+  });
+});
+
+test("parses empty querystring", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+test("parses querystring with multiple key value pairs", () => {
+  expect(parseQueryString("name=Karim&age=20")).toEqual({
+    "name": "Karim",
+    "age": "20"
   });
 });
+
+test("parses querystring with empty value", () => {
+  expect(parseQueryString("name=")).toEqual({
+    "name": ""
+  });
+});

Sprint-2/implement/tally.js

@@ -1,3 +1,13 @@
-function tally() {}
+function tally(items) {
+    if (!Array.isArray(items)) {
+        throw new Error('Items must be an array');
+    }
+    const counts = Object.create(null);
+    for (const item of items) {
+        counts[item] = (counts[item] || 0) + 1;
+    }
+    return counts;
+
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -23,12 +23,21 @@ 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 counts unique items", () => {
+  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 throws an error for invalid input", () => {
+  expect(() => tally("not an array")).toThrow("Items must be an array");
+});
+

Sprint-2/interpret/invert.js

@@ -10,20 +10,49 @@ function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
 // a) What is the current return value when invert is called with { a : 1 }
 
+// It returns { key: 1 } because invertedObj.key always writes the word "key"
+
+//---------------------------------------------------------------------------------------//
+
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
 
+// It returns { key: 2 } because it keeps overwriting the same "key" each time
+
+//---------------------------------------------------------------------------------------//
+
 // c) What is the target return value when invert is called with {a : 1, b: 2}
 
+// It should return { "1": "a", "2": "b" } because the keys and values are swapped
+
+//---------------------------------------------------------------------------------------//
+
 // c) What does Object.entries return? Why is it needed in this program?
 
+// Object.entries turns the object into an array like [["a", 1], ["b", 2]]
+// We need it so we can loop through each key and value one by one
+
+//---------------------------------------------------------------------------------------//
+
 // d) Explain why the current return value is different from the target output
 
+// Because invertedObj.key writes the word "key" literally
+// instead of using the actual value as the key
+// changing it to invertedObj[value] = key fixes this
+
+//---------------------------------------------------------------------------------------//
+
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+
+// Fixed by changing invertedObj.key = value to invertedObj[value] = key
+// Tests are written in invert.test.js
+
+
+module.exports = invert;

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,16 @@
+const invert = require("./invert.js");
+
+// Test 1 swaps the keys and values
+test("invert swaps keys and values", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ "1": "a", "2": "b" });
+});
+
+// Test 2 empty object should return empty object
+test("invert on an empty object returns an empty object", () => {
+  expect(invert({})).toEqual({});
+});
+
+// Test 3 single key value pair
+test("invert works with a single pair", () => {
+    expect(invert({ x: 10 })).toEqual({ "10": "x" });
+});