London | 26-ITP-May | Liridona Shehu | Sprint 2 | Module Data Groups

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

@@ -2,6 +2,9 @@
 
 // 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
+// To loop over object keys we use for in loop.In this case we  declared a variable `value`
+// to hold the property name. In this case we use bracket notation instead of dot notation to
+// access property value.
 
 const author = {
   firstName: "Zadie",
@@ -11,6 +14,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
-  console.log(value);
+for (const value in author) {
+  console.log(author[value]);
 }

Sprint-2/debug/recipe.js

@@ -11,5 +11,5 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ ingredients:
+${recipe.ingredients.join("\n")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,7 @@
-function contains() {}
+function contains(object, propertyName) {
+  if (Object.hasOwn(object, propertyName)) {
+    return true;
+  } else return false;
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -16,20 +16,39 @@ as the object doesn't contains a key of 'c'
 // Given a contains function
 // When passed an object and a property name
 // Then it should return true if the object contains the property, false otherwise
+test("given an object with property, should return true if contains the property otherwise false", () => {
+  expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
+  expect(contains({ a: 1, b: 2 }, "c")).toBe(false);
+});
 
 // 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({})).toBe(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("given an object with property, should return true if contains the property", () => {
+  expect(
+    contains({ firstName: "Chris", surname: "Marin", age: 21 }, "firstName")
+  ).toBe(true);
+});
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
-
+test("given an object with property, should return false if  does not contains the property", () => {
+  expect(
+    contains({ firstName: "Chris", surname: "Marin", age: 21 }, "job")
+  ).toBe(false);
+});
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+
+test("given an array, should return false", () => {
+  expect(contains([1, 2, 3], "a")).toBe(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,10 @@
-function createLookup() {
+function createLookup(data) {
   // implementation here
+  const newObject = {};
+  for (const [country, currency] of data) {
+    newObject[country] = currency;
+  }
+  return newObject;
 }
 
 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

@@ -1,15 +1,35 @@
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
+  if (
+    queryString === null ||
+    queryString === undefined ||
+    queryString.length === 0
+  ) {
     return queryParams;
   }
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    if (pair === "") {
+      continue;
+    }
+    const equalIndex = pair.indexOf("=");
+    let key;
+    let value;
+
+    if (equalIndex === -1) {
+      key = pair;
+      value = "";
+    } else {
+      key = pair.slice(0, equalIndex);
+      value = pair.slice(equalIndex + 1);
+    }
+    key = key.replace(/\+/g, " ");
+    value = value.replace(/\+/g, " ");
+    key = decodeURIComponent(key);
+    value = decodeURIComponent(value);
     queryParams[key] = value;
   }
-
   return queryParams;
 }
 

Sprint-2/implement/querystring.test.js

@@ -3,7 +3,7 @@
 // Below are some test cases the implementation doesn't handle well.
 // Fix the implementation for these tests, 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("should parse values containing '='", () => {
   expect(parseQueryString("equation=a=b-2")).toEqual({
@@ -37,12 +37,17 @@ test("should replace '+' by ' '", () => {
   });
 });
 
+test("should return an empty object for null or undefined", () => {
+  expect(parseQueryString(null)).toEqual({});
+  expect(parseQueryString(undefined)).toEqual({});
+});
+
 // Stretch exercise: Handling query strings that contain identical keys
 
-// Delete this test if you are not working on this optional case
-test("should store values of a key in an array when the key has 2 or more values", () => {
-  expect(parseQueryString("key=value1&key=value2&key=value3&foo=bar")).toEqual({
-    key: ["value1", "value2", "value3"],
-    foo: "bar",
-  });
-});
+// // Delete this test if you are not working on this optional case
+// test("should store values of a key in an array when the key has 2 or more values", () => {
+//   expect(parseQueryString("key=value1&key=value2&key=value3&foo=bar")).toEqual({
+//     key: ["value1", "value2", "value3"],
+//     foo: "bar",
+//   });
+// });

Sprint-2/implement/tally.js

@@ -1,3 +1,15 @@
-function tally() {}
+function tally(items) {
+  if (!Array.isArray(items)) {
+    throw new Error("Invalid input");
+  }
+  const itemsObj = {};
+  for (const item of items) {
+    if (item === undefined || item === null) continue;
+    if (itemsObj[item] === undefined) {
+      itemsObj[item] = 1;
+    } else itemsObj[item]++;
+  }
+  return itemsObj;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -11,24 +11,52 @@ const tally = require("./tally.js");
  *
  * tally(['a']), target output: { a: 1 }
  * tally(['a', 'a', 'a']), target output: { a: 3 }
- * tally(['a', 'a', 'b', 'c']), target output: { a : 2, b: 1, c: 1 }
+ * tally([c]), target output: { a : 2, b: 1, c: 1 }
  */
 
 // Acceptance criteria:
 
 // 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, should return an object containing the count for each unique item", () => {
+  expect(tally(["a", "b", "c", "d"])).toEqual({ a: 1, b: 1, c: 1, d: 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 with duplicate items, should return counts for each unique item", () => {
+  expect(tally(["a", "a", "a", "b", "b", "c"])).toEqual({ a: 3, b: 2, c: 1 });
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("Given an invalid input like a string, it should throw an error", () => {
+  expect(() => tally("hello")).toThrow();
+});
+
+// Given undefined  or null
+// When passed to tally
+// Then it should ignore these values
+test("Given undefined  or null, should ignore these values", () => {
+  expect(() => {
+    tally([
+      "apple",
+      "banana",
+      "apple",
+      "orange",
+      "banana",
+      undefined,
+      null,
+    ]).toEqual(["apple", "banana", "apple", "orange", "banana"]);
+  });
+});

Sprint-2/interpret/invert.js

@@ -10,20 +10,26 @@ 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 }
+// The current return value when inverted is called with { a: 1 } is{ key: 1 }
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// The current return value when inverted is called with { a: 1, b: 2 } is { key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// The target return value when invert is called with { a : 1, b: 2 } is { 1 : a, 2: b }
 
 // c) What does Object.entries return? Why is it needed in this program?
+// Object.entries return an array where each element of array is a pair key-value. It is needed in this program because an object can not be looped with for...of.
 
-// d) Explain why the current return value is different from the target output
+// d) Explain why the current return value is different from the target output.
+// The current return value is different from the target output because when we apply
+//invertedObj.key = value we are declaring a new key and assigning the value
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,24 @@
+const invert = require("./invert.js");
+
+// Given an empty object
+// When invert is passed this object
+// Then it should return an empty object.
+test("Given an empty object,should return an empty object", () => {
+  expect(invert({})).toEqual({});
+});
+
+// Given an object
+// When invert is passed this object
+// Then it should swap the keys and values in the object
+test("Given an object, should swap the keys and values in the object", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+  expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+  expect(invert({ a: 1, b: 2, c: 3, d: 4 })).toEqual({
+    1: "a",
+    2: "b",
+    3: "c",
+    4: "d",
+  });
+});
+
+test("Given an empty object, should swap the keys and values in the object", () => {});