London | 26-ITP-May | Damilola Odumosu | Sprint 2 | Coursework

Sprint-2/debug/address.js

@@ -1,6 +1,6 @@
 // Predict and explain first...
 
-// This code should log out the houseNumber from the address object
+// This code should log out the houseNumber from the address object,
 // but it isn't working...
 // Fix anything that isn't working
 
@@ -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

@@ -10,7 +10,7 @@ const author = {
   age: 40,
   alive: true,
 };
-
-for (const value of author) {
-  console.log(value);
+//An object is not directly iterable, if we want to log out the values we can use a for in loop
+for (const key in author) {
+  console.log(author[key]);
 }

Sprint-2/debug/recipe.js

@@ -11,5 +11,7 @@ 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 +1,7 @@
-function contains() {}
-
+function contains(object, property) {
+  if (typeof object !== "object" || Array.isArray(object) || object === null) {
+    throw new Error("Invalid data type");
+  }
+  return Object.hasOwn(object, property);
+}
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -8,7 +8,7 @@ E.g. contains({a: 1, b: 2}, 'a') // returns true
 as the object contains a key of 'a'
 
 E.g. contains({a: 1, b: 2}, 'c') // returns false
-as the object doesn't contains a key of 'c'
+as the object doesn't contain a key of 'c'
 */
 
 // Acceptance criteria:
@@ -17,19 +17,70 @@ as the object doesn't contains a key of 'c'
 // When passed an object and a property name
 // Then it should return true if the object contains the property, false otherwise
 
+test(
+  "when passed an object and a property name, should return true if the object " +
+    "contains the property",
+  () => {
+    const obj = {
+      name: "dami",
+      age: 34,
+      height: 5.3,
+      location: "London",
+    };
+    const propertyNameCheck = "name";
+    const expected = true;
+    const result = contains(obj, propertyNameCheck);
+    expect(result).toBe(expected);
+  }
+);
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
 
+test("given an empty object, should return false", () => {
+  const obj = {};
+  const propertyNameCheck = "a";
+  const expected = false;
+  const result = contains(obj, propertyNameCheck);
+  expect(result).toBe(expected);
+});
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+//this test requirement is cvered on line 21
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
-
+test(
+  "when passed an object and a property name, should return false if the object " +
+    "does not contain the property.",
+  () => {
+    const obj = {
+      title: "Things fall apart",
+      year: 1958,
+      publisher: "pan-macmillan",
+    };
+    const propertyNameCheck = "location";
+    const expected = false;
+    const result = contains(obj, propertyNameCheck);
+    expect(result).toBe(expected);
+  }
+);
+test("should throw an error when the input is an array, even if the specified key exists", () => {
+  const arr = ["apple", "banana"];
+  const arrIndex = 0;
+  expect(() => contains(arr, arrIndex)).toThrow("Invalid data type");
+});
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+
+test.each([["hello"], [123], [true], [undefined], [null]])(
+  "throws an error when input is %p",
+  (type) => {
+    expect(() => {
+      contains(type, "A");
+    }).toThrow("Invalid data type");
+  }
+);

Sprint-2/implement/lookup.js

@@ -1,5 +1,28 @@
-function createLookup() {
-  // implementation here
-}
+function createLookup(arr) {
+  if (!Array.isArray(arr)) {
+    throw new Error("invalid data type entered");
+  }
+  if (arr.length === 0) {
+    throw new Error("country and currency code not entered");
+  }
+
+  const objectLookup = {};
 
+  for (const pair of arr) {
+    if (!Array.isArray(pair)) {
+      throw new Error("Each item must be an array.");
+    }
+    if (pair.length !== 2) {
+      throw new Error(
+        "Each inner array must contain exactly two elements: a key and a value"
+      );
+    }
+    const [country, currency] = pair;
+    if (country === currency) {
+      throw new Error("Country code and currency code cannot be the same");
+    }
+    objectLookup[country] = currency;
+  }
+  return objectLookup;
+}
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,7 +1,5 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
 /*
 
 Create a lookup object of key value pairs from an array of code pairs
@@ -33,3 +31,48 @@ It should return:
    'CA': 'CAD'
  }
 */
+
+test("when passed an empty array, throw an error", () => {
+  expect(() => {
+    createLookup([]);
+  }).toThrow("country and currency code not entered");
+});
+
+test("when given an array of arrays containing two elements, returns an object of key-value pairs", () => {
+  const input = [
+    ["US", "USD"],
+    ["CA", "CAD"],
+    ["NG", "NIG"],
+  ];
+  const expected = {
+    US: "USD",
+    CA: "CAD",
+    NG: "NIG",
+  };
+  const result = createLookup(input);
+  expect(result).toEqual(expected);
+});
+
+test.each(["hello", 123, true, null, undefined, {}])(
+  "throws an error when input is %p",
+  (input) => {
+    expect(() => {
+      createLookup(input);
+    }).toThrow("invalid data type entered");
+  }
+);
+
+test("when given an array containing more than 2 elements, throw error", () => {
+  const input = [["US", "USD", "U"]];
+  expect(() => {
+    createLookup(input);
+  }).toThrow(
+    "Each inner array must contain exactly two elements: a key and a value"
+  );
+});
+
+test("when given an array, if country code !=== currency code, throw an error", () => {
+  expect(() => {
+    createLookup([["US", "US"]]);
+  }).toThrow("Country code and currency code cannot be the same");
+});

Sprint-2/implement/querystring.js

@@ -5,12 +5,22 @@ function parseQueryString(queryString) {
   }
   const keyValuePairs = queryString.split("&");
 
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+  for (let pair of keyValuePairs) {
+    if (pair === "") {
+      continue;
+    }
+    if (pair.includes("+")) {
+      pair = pair.replaceAll("+", " ");
+    }
+    const indexOfFirst = pair.indexOf("=");
+    if (indexOfFirst === -1) {
+      queryParams[pair] = "";
+    } else {
+      let key = decodeURIComponent(pair.slice(0, indexOfFirst));
+      let value = decodeURIComponent(pair.slice(indexOfFirst + 1));
+      queryParams[key] = value;
+    }
   }
-
   return queryParams;
 }
-
 module.exports = parseQueryString;

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({
@@ -36,13 +36,3 @@ test("should replace '+' by ' '", () => {
     "full name": "John Doe",
   });
 });
-
-// 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",
-  });
-});

Sprint-2/implement/tally.js

@@ -1,3 +1,13 @@
-function tally() {}
-
+function tally(arr) {
+  if (!Array.isArray(arr)) {
+    throw new Error('Invalid data type entered"');
+  }
+  if (arr.length === 0) {
+    return {};
+  }
+  return arr.reduce((acc, cur) => {
+    acc[cur] = (acc[cur] || 0) + 1;
+    return acc;
+  }, Object.create(null));
+}
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -19,16 +19,42 @@ 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("", () => {
+  const input = ["hey", "hi", "hello", "hi", "word", "picnic", "book"];
+  const expected = {
+    hey: 1,
+    hi: 2,
+    hello: 1,
+    word: 1,
+    picnic: 1,
+    book: 1,
+  };
+  const result = tally(input);
+  expect(result).toEqual(expected);
+});
 // 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", () => {
+  const input = [];
+  const expected = {};
+  const result = tally(input);
+  expect(result).toEqual(expected);
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+//Test on line 22 covers this
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test.each([undefined, null, {}, "hello", 123, true])(
+  "throws when input is %p",
+  (input) => {
+    expect(() => {
+      tally(input).toThrow("Invalid data type entered");
+    });
+  }
+);

Sprint-2/interpret/invert.js

@@ -7,23 +7,39 @@
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
 function invert(obj) {
-  const invertedObj = {};
-
-  for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+  if (typeof obj !== "object" || obj === null || Array.isArray(obj)) {
+    throw new Error("Enter a valid object");
+  }
+  if (Object.keys(obj).length === 0) {
+    return {};
   }
 
+  const invertedObj = {};
+  for (let [key, value] of Object.entries(obj)) {
+    invertedObj[value] = key;
+  }
   return invertedObj;
 }
-
+module.exports = invert;
 // a) What is the current return value when invert is called with { a : 1 }
+// The current value is: { key: 1 }
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// The current value is: { key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// The target return value should be:
+//{ "1" : "a", "2" : "b"}
 
 // c) What does Object.entries return? Why is it needed in this program?
+//Object.entries returns an array of a key-value pair. we need object.entries
+// because we cannot directly loop over an object, so by using the method
+// it turns it into an array we can loop over
 
 // d) Explain why the current return value is different from the target output
+//The current return uses a dot notation with the variable 'key', when we use a
+// dot notation with a variable it doesn't get the value of the variable but
+// instead uses the literal word as the key. when we change it to a bracket notation
+// it reads the variable and uses that for the key, we however need to swap the return around and return value = key.
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)