Manchester | 26-ITP-Jan | Liban Jama | Sprint 2 | Data Groups

Sprint-2/debug/address.js

@@ -4,6 +4,7 @@
 // but it isn't working...
 // Fix anything that isn't working
 
+// i predict that it will fail straight away as value for houseNumber was not in a string
 const address = {
   houseNumber: 42,
   street: "Imaginary Road",
@@ -12,4 +13,6 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(`My house number is ${address.houseNumber}`);
+
+// the issue was that it was looking for the property [0] so i changed it to dot notation .houseNumber in the console.log

Sprint-2/debug/author.js

@@ -11,6 +11,7 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
 }
+// Objects are not iterable, so for...of can’t be used on them unless you convert them to an array (e.g. with Object.values).

Sprint-2/debug/recipe.js

@@ -4,12 +4,17 @@
 // Each ingredient should be logged on a new line
 // How can you fix it?
 
+// it should print the recipe title, how many people people it serves and lists the ingredients.
+
 const recipe = {
   title: "bruschetta",
   serves: 2,
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
+console.log(`${recipe.title} 
+  serves ${recipe.serves}
   ingredients:
-${recipe}`);
+${recipe.ingredients.join("\n")}`);
+
+// it printed [object Object], this is because ${recipe} tries to print the whole object, which shows as [object Object] instead of useful data. This was fixed by using ${recipe.ingredients} (and .join(", ")) to display the ingredients properly.

Sprint-2/implement/contains.js

@@ -1,3 +1,9 @@
-function contains() {}
+function contains(object, propertyName) {
+  if (typeof object !== "object" || object === null || Array.isArray(object)) {
+    // if user passes something that is not an object, or object is null/array, then return false.
+    return false;
+  }
+  return Object.hasOwn(object, propertyName);
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -20,16 +20,37 @@ 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", () => {
+  expect(contains({}, "ball")).toEqual(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
-
+test("contains an object with properties, returns true", () => {
+  expect(contains({ foot: "ball" }, "foot")).toEqual(true);
+});
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("should return false when the object does not contain the property", () => {
+  expect(contains({ foot: "ball" }, "basket")).toEqual(false);
+});
 
 // Given invalid parameters like an array
 // When passed to contains
-// Then it should return false or throw an error
+// Then it should return false
+test("should return false when input is not an object", () => {
+  expect(contains([], "a")).toEqual(false);
+});
+
+// Given invalid parameter e.g. null
+// When passed to contains
+// Then it should return false
+test("should return false when input is null", () => {
+  expect(contains(null, "a")).toEqual(false);
+});
+
+test("should return false when input is an array even if propertyName is a valid key", () => {
+  expect(contains(["x", "y"], "0")).toEqual(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,19 @@
-function createLookup() {
-  // implementation here
+function createLookup(list) {
+  // key = country code e.g. 'US'
+  // value = currency code e.g. 'USD'
+  // input = array of [country, currency]
+  // process = go through each pair, add to object
+  // output = object { country: currency }
+
+  // declare a variable and store empty object
+  // loop through the array
+  // while in the loop take each item and add it to the object
+  let items = {};
+
+  for (let i = 0; i < list.length; i++) {
+    items[list[i][0]] = list[i][1];
+  }
+  return items;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,17 @@
 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 expectedOutput = {
+    US: "USD",
+    CA: "CAD",
+  };
+
+  expect(createLookup(input)).toEqual(expectedOutput);
+});
 
 /*
 

Sprint-2/implement/querystring.js

@@ -1,12 +1,23 @@
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
-    return queryParams;
-  }
-  const keyValuePairs = queryString.split("&");
+  if (queryString.length === 0) return queryParams;
+
+  const pairs = queryString.split("&");
+
+  for (const pair of pairs) {
+    const index = pair.indexOf("=");
+    // if there is a key but no equals, return empty string for value.
+    let key;
+    let value;
+    if (index === -1) {
+      key = pair;
+      value = "";
+    } else {
+      key = pair.slice(0, index).trim();
+      value = pair.slice(index + 1).trim();
+    }
 
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    if (!key) continue;
     queryParams[key] = value;
   }
 

Sprint-2/implement/querystring.test.js

@@ -3,10 +3,47 @@
 // Below is one test case for an edge case the implementation doesn't handle well.
 // Fix the implementation for this test, and try to think of as many other edge cases as possible - write tests and fix those too.
 
-const parseQueryString = require("./querystring.js")
+const parseQueryString = require("./querystring.js");
 
 test("parses querystring values containing =", () => {
   expect(parseQueryString("equation=x=y+1")).toEqual({
-    "equation": "x=y+1",
+    equation: "x=y+1",
+  });
+  expect(parseQueryString("page=1")).toEqual({
+    page: "1",
+  });
+  expect(parseQueryString("name=Ali")).toEqual({
+    name: "Ali",
+  });
+});
+
+test("parses querystring values containing &", () => {
+  expect(parseQueryString("key1=value1&key2=value2")).toEqual({
+    key1: "value1",
+    key2: "value2",
+  });
+  expect(parseQueryString("name=Ayub&colour=blue")).toEqual({
+    name: "Ayub",
+    colour: "blue",
+  });
+});
+
+test("handles malformed querystrings", () => {
+  // if value is empty, return empty string for value.
+  expect(parseQueryString("key=")).toEqual({
+    key: "",
+  });
+  // if key is empty don't return anything.
+  expect(parseQueryString("=value")).toEqual({});
+  // if there is a key but no equals, return empty string for value.
+  expect(parseQueryString("key")).toEqual({ key: "" });
+  // if key is empty and value is empty, don't return anything for that item
+  expect(parseQueryString("key1=value1&=&key2=value2")).toEqual({
+    key1: "value1",
+    key2: "value2",
+  });
+  expect(parseQueryString("key1=value1&&key2=value2")).toEqual({
+    key1: "value1",
+    key2: "value2",
   });
 });

Sprint-2/implement/tally.js

@@ -1,3 +1,16 @@
-function tally() {}
+function tally(items) {
+  if (!Array.isArray(items)) {
+    throw new Error("Input must be an array");
+  }
+
+  const plainObject = Object.create(null);
+
+  const itemsObject = items.reduce((acc, item) => {
+    acc[item] = (acc[item] || 0) + 1;
+    return acc;
+  }, plainObject);
+
+  return itemsObject;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -19,16 +19,34 @@ 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("tally returns counts 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("tally handles duplicate items", () => {
+  expect(tally(["a", "a", "a"])).toEqual({ a: 3 });
+});
 
 // 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("invalid")).toThrow();
+});
+
+// Given an input that has the same name as a prototype method
+// When passed to tally
+// Then it should return counts for each unique item
+test("tally returns correct output for all strings ", () => {
+  expect(tally(["toString", "toString"])).toEqual({ toString: 2 });
+});

Sprint-2/interpret/invert.js

@@ -10,20 +10,22 @@ function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
-
+// console.log(invert({ a: 1, b: 2 }), "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?
-
+// The Object.entries() static method returns an array of a given object's own enumerable string-keyed property key-value pairs. It returns an array with the object's key-value pairs. e.g. [ [ 'a', 1 ], [ 'b', 2 ] ]
 // d) Explain why the current return value is different from the target output
-
+// This is because the function is not correctly inverting the key and value.
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+
+module.exports = invert;

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,16 @@
+const invert = require("../interpret/invert");
+
+test(`Should return {"10": "x", "20": "y"} when given { x: 10, y: 20 } `, () => {
+  expect(invert({ x: 10, y: 20 })).toEqual({ 10: "x", 20: "y" });
+});
+
+test(`Should return {"2": "bounce", "100": "high"} when given { bounce: 2, high: 100 } `, () => {
+  expect(invert({ bounce: 2, high: 100 })).toEqual({
+    2: "bounce",
+    100: "high",
+  });
+});
+
+test(`Should return {"foot": "ball"} when given { "ball": "foot" } `, () => {
+  expect(invert({ ball: "foot" })).toEqual({ foot: "ball" });
+});