Manchester | 26-ITP-May | Samreen Amjad | Sprint 2 | Exercises

Sprint-2/debug/address.js

@@ -1,5 +1,7 @@
 // Predict and explain first...
 
+// This will fail because to parse from an object requires a key, not an index value
+
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -12,4 +14,4 @@ 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

@@ -1,4 +1,5 @@
 // Predict and explain first...
+// The for...of loop only works with iterable objects, such as arrays 
 
 // 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
@@ -11,6 +12,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
-}
+}

Sprint-2/debug/recipe.js

@@ -1,5 +1,13 @@
 // Predict and explain first...
 
+//The program will not display the ingredients correctly. Instead, it will show something like:
+//bruschetta serves 2
+//ingredients:
+//[object Object]
+
+//The issue is that `recipe` is an object. JavaScript cannot display the whole object inside a string, so it shows `[object Object]`. You need to access the specific values you want, like the ingredients array, and format them separately.
+
+
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
 // How can you fix it?
@@ -11,5 +19,5 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ingredients:
+${recipe.ingredients.join("\n")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,5 @@
-function contains() {}
+function contains(array, target) {
+  return array.includes(target);
+}
 
-module.exports = contains;
+module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -1,35 +1,43 @@
-const contains = require("./contains.js");
-
-/*
-Implement a function called contains that checks an object contains a
-particular property
-
-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'
-*/
-
-// Acceptance criteria:
-
-// 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
-
-// Given an empty object
-// When passed to contains
-// Then it should return false
-test.todo("contains on empty object returns false");
-
-// Given an object with properties
-// When passed to contains with an existing property name
-// Then it should return true
-
-// Given an object with properties
-// When passed to contains with a non-existent property name
-// Then it should return false
-
-// Given invalid parameters like an array
-// When passed to contains
-// Then it should return false or throw an error
+describe("contains", () => {
+  // Given an empty object
+  // When passed to contains
+  // Then it should return false
+  it("contains on empty object returns false", () => {
+    const object = {};
+    const property = "a";
+    expect(contains(object, property)).toEqual(false);
+  });
+
+  // Given an object with properties
+  // When passed to contains with an existing property name
+  // Then it should return true
+  it("object contains property returns true", () => {
+    const object = { a: 1, b: 2 };
+    const property = "a";
+    expect(contains(object, property)).toEqual(true);
+  });
+
+  // Given an object with properties
+  // When passed to contains with a non-existent property name
+  // Then it should return false
+  it("object does not contain property returns false", () => {
+    const object = { a: 1, b: 2 };
+    const property = "c";
+    expect(contains(object, property)).toEqual(false);
+  });
+
+  // Given invalid parameters like an array
+  // When passed to contains
+  // Then it should return false or throw an error
+  it("given invalid parameter (an array) returns false or throws an error", () => {
+    expect(contains([], [])).toEqual(false);
+    expect(contains(["a", 1], 1)).toEqual(false);
+    expect(contains({ a: 1, b: 2 }, ["a"])).toEqual(false);
+  });
+
+  it("given null returns false", () => {
+    expect(contains(null, "a")).toEqual(false);
+    expect(contains({ a: 1, b: 2 }, null)).toEqual(false);
+    expect(contains(null, null)).toEqual(false);
+  });
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,9 @@
-function createLookup() {
-  // implementation here
+function createLookup(arrayOfArrays) {
+  const lookup = {};
+  for (const array of arrayOfArrays) {
+    lookup[array[0]] = array[1];
+  }
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,35 +1,17 @@
 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
-
-Acceptance Criteria:
-
-Given
- - An array of arrays representing country code and currency code pairs
-   e.g. [['US', 'USD'], ['CA', 'CAD']]
-
-When
- - createLookup function is called with the country-currency array as an argument
-
-Then
- - It should return an object where:
- - The keys are the country codes
- - The values are the corresponding currency codes
-
-Example
-Given: [['US', 'USD'], ['CA', 'CAD']]
-
-When
-createLookup(countryCurrencyPairs) is called
-
-Then
-It should return:
- {
-   'US': 'USD',
-   'CA': 'CAD'
- }
-*/
+describe("createLookup", () => {
+  it("creates a country currency code lookup for multiple codes", () => {
+    const arrayOfArrays = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+      ["UK", "GBP"],
+    ];
+    expect(createLookup(arrayOfArrays)).toEqual({
+      US: "USD",
+      CA: "CAD",
+      UK: "GBP",
+    });
+  });
+});

Sprint-2/implement/querystring.js

@@ -3,14 +3,29 @@ function parseQueryString(queryString) {
   if (queryString.length === 0) {
     return queryParams;
   }
+
+  // Replaces + with space
+  queryString = queryString.replaceAll("+", " ");
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    f (pair !== "") {
+      let index = pair.indexOf("=");
+      if (!pair.includes("=")) {
+        index = pair.length;
+      }
+      const rawKey = pair.slice(0, index);
+      const rawValue = pair.slice(index + 1);
+
+      // Remove percentage-encoded characters
+      const key = decodeURIComponent(rawKey);
+      const value = decodeURIComponent(rawValue);
+
+      queryParams[key] = value;
+    }
   }
 
   return queryParams;
 }
 
-module.exports = parseQueryString;
+

Sprint-2/implement/querystring.test.js

@@ -1,48 +1,37 @@
-// In the prep, we implemented a function to parse query strings.
-// Unfortunately, it contains several bugs!
-// 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")
-
-test("should parse values containing '='", () => {
-  expect(parseQueryString("equation=a=b-2")).toEqual({
-    equation: "a=b-2",
-  });
-});
-
-test("should ignore empty key-value pairs", () => {
-  expect(parseQueryString("key1=value1&&key2=value2&")).toEqual({
-    key1: "value1",
-    key2: "value2",
-  });
-});
-
-test("should accept empty string as key or as value", () => {
-  expect(parseQueryString("=value")).toEqual({ "": "value" });
-  expect(parseQueryString("key")).toEqual({ key: "" });
-  expect(parseQueryString("key=")).toEqual({ key: "" });
-  expect(parseQueryString("=")).toEqual({ "": "" });
-});
-
-test("should decode percent-encoded characters", () => {
-  expect(parseQueryString("%24half=1%2F2")).toEqual({
-    $half: "1/2",
-  });
-});
-
-test("should replace '+' by ' '", () => {
-  expect(parseQueryString("full+name=John+Doe")).toEqual({
-    "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",
-  });
-});
+function parseQueryString(queryString) {
+  const queryParams = {};
+
+  if (queryString.length === 0) {
+    return queryParams;
+  }
+
+  const keyValuePairs = queryString.split("&");
+
+  for (const pair of keyValuePairs) {
+    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 = decodeURIComponent(key.replaceAll("+", " "));
+    value = decodeURIComponent(value.replaceAll("+", " "));
+
+    queryParams[key] = value;
+  }
+
+  return queryParams;
+}
+
+module.exports = parseQueryString;

Sprint-2/implement/tally.js

@@ -1,3 +1,13 @@
-function tally() {}
-
+function tally(array) {
+  if (!Array.isArray(array)) {
+    throw new Error("Invalid array");
+  }
+  const count = Object.create(null);
+  array.forEach((item) => {
+    if (item in count) {
+      count[item] += 1;
+    } else count[item] = 1;
+  });
+  return count;
+}
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -20,15 +20,34 @@ const tally = require("./tally.js");
 // When passed an array of items
 // Then it should return an object containing the count for each unique item
 
-// 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");
+describe("tally", () => {
+  // Given an empty array
+  // When passed to tally
+  // Then it should return an empty object
+  it("tally on an empty array returns an empty object", () => {
+    const array = [];
+    expect(tally(array)).toEqual({});
+  });
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
 
+it("tally returns counts for each unique item", () => {
+    expect(tally(["a", "a", "b", "c"])).toEqual({ a: 2, b: 1, c: 1 });
+    expect(tally(["toString", "toString"])).toEqual({ toString: 2 });
+  });
+
+
+
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+
+it("tally on an empty array returns an empty object", () => {
+    const array = "string";
+    expect(() => {
+      tally(array);
+    }).toThrow("Invalid array");
+  });
+});