London | 26-ITP-May | Dagim Daniel | Sprint 2 | All Section Exercises

Sprint-2/debug/address.js

@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// i think its because the address is not used as an array but as an 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

@@ -1,8 +1,8 @@
 // Predict and explain first...
-
+//i think its because value is not used as a parameter of an object, and author is an object not an ordered list Array.
 // 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
-
+// i found that object literals are not iterative because they have no orders
 const author = {
   firstName: "Zadie",
   lastName: "Smith",
@@ -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

@@ -1,5 +1,9 @@
 // Predict and explain first...
-
+/*
+console.log(`${recipe.title} serves ${recipe.serves}
+  ingredients:
+${recipe}`);// here it misses recipe.ingredients 
+*/
 // 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?
@@ -12,4 +16,4 @@ const recipe = {
 
 console.log(`${recipe.title} serves ${recipe.serves}
   ingredients:
-${recipe}`);
+${recipe.ingredients.join("\n")}`); // this make the list to be logged on a new line - not predicted at first

Sprint-2/implement/contains.js

@@ -1,3 +1,18 @@
-function contains() {}
-
+function contains(keyInput, valueInput) {
+  if (
+    keyInput == null ||
+    typeof keyInput !== "object" ||
+    Array.isArray(keyInput)
+  ) {
+    return false;
+  } else {
+    for (const key in keyInput) {
+      if (key == valueInput) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+// make values like null, undefined ,1234, true,"Abc" to be consider invalid and return false same as array
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -1,35 +1,28 @@
 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
+test("Give a contains with object and property and if the object contains the property returns true", () => {
+  expect(contains({ a: 1, b: 2 }, "b")).toEqual(true);
+});
+
+test("Give a contains with empty object and  when passed to contains it returns false", () => {
+  expect(contains({}, "y")).toEqual(false);
+});
+
+test("Give a contains with object and property and if the property is non-existent returns false", () => {
+  expect(contains({ a: 1, b: 2 }, "z")).toEqual(false);
+});
+
+test("Give invalid parameter in this case array when passed to contains it returns false", () => {
+  expect(contains(["a", 2, "b", 3, 2], 2)).toEqual(false);
+});
+
+test("Give invalid parameter in this case empty  when passed to contains it returns false", () => {
+  expect(contains(null)).toEqual(false);
+});
+test("returns false for undefined", () => {
+  expect(contains(undefined, "key")).toEqual(false);
+});
+
+test("returns false for numbers", () => {
+  expect(contains(1234, "key")).toEqual(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,9 @@
-function createLookup() {
-  // implementation here
+function createLookup(countryCurrencyPairs) {
+  pairs = {};
+  for (const [country, currency] of countryCurrencyPairs) {
+    pairs[country] = currency;
+  }
+  return pairs;
 }
 
 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'
- }
-*/
+test("create a country currency code lookup for a single codes", () => {
+  expect(createLookup([["UK", "GBP"]])).toEqual({ UK: "GBP" });
+});
+test("creates an empty country currency code returns empty lookup", () => {
+  expect(createLookup([])).toEqual({});
+});
+test("creates a country currency code lookup for multiple codes", () => {
+  expect(
+    createLookup([
+      ["US", "USD"],
+      ["CA", "CAD"],
+      ["UK", "GBP"],
+    ])
+  ).toEqual({ US: "USD", CA: "CAD", UK: "GBP" });
+});

Sprint-2/implement/querystring.js

@@ -1,13 +1,39 @@
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
+  if (!queryString) {
     return queryParams;
   }
+
+  // 1. Split on '&' to get individual key-value pairs
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    // Skip completely empty segments from '&&' or trailing '&'
+    if (!pair) continue;
+
+    // 2. Split on '=' separating key and value
+    const eqIndex = pair.indexOf("=");
+    let rawKey, rawValue;
+
+    if (eqIndex === -1) {
+      // Key with no '=' (e.g. "key")
+      rawKey = pair;
+      rawValue = "";
+    } else {
+      rawKey = pair.slice(0, eqIndex);
+      rawValue = pair.slice(eqIndex + 1);
+    }
+
+    // 3. Replace '+' with ' ' first, then decode URL percent-encoded values
+    const key = decodeURIComponent(rawKey.replace(/\+/g, " "));
+    const value = decodeURIComponent(rawValue.replace(/\+/g, " "));
+
+    // 4. Handle identical keys (stretch goal)
+    if (Object.hasOwn(queryParams, key)) {
+      queryParams[key] = [].concat(queryParams[key], value);
+    } else {
+      queryParams[key] = value;
+    }
   }
 
   return queryParams;

Sprint-2/implement/querystring.test.js

@@ -1,9 +1,4 @@
-// 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")
+const parseQueryString = require("./querystring.js");
 
 test("should parse values containing '='", () => {
   expect(parseQueryString("equation=a=b-2")).toEqual({
@@ -37,9 +32,6 @@ test("should replace '+' by ' '", () => {
   });
 });
 
-// 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"],

Sprint-2/implement/tally.js

@@ -1,3 +1,12 @@
-function tally() {}
-
+function tally(items) {
+  if (!Array.isArray(items)) {
+    throw new Error("Invalid input!");
+  }
+  const result = {};
+  for (const item of items) {
+    const count = Object.hasOwn(result, item) ? result[item] : 0;
+    result[item] = count + 1;
+  }
+  return result;
+}
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -1,34 +1,22 @@
 const tally = require("./tally.js");
 
-/**
- * tally array
- *
- * In this task, you'll need to implement a function called tally
- * that will take a list of items and count the frequency of each item
- * in an array
- *
- * For example:
- *
- * 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 }
- */
+test("given an array of items an object containing the counter for each item", () => {
+  expect(tally(["a", "a"])).toEqual({ a: 2 });
+});
 
-// Acceptance criteria:
+test("tally on an empty array returns an empty object", () => {
+  expect(tally([])).toEqual({});
+});
 
-// 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 an object containing the counter for each item", () => {
+  expect(tally(["a", "a", "c", "b", "b", "d"])).toEqual({
+    a: 2,
+    c: 1,
+    b: 2,
+    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");
-
-// Given an array with duplicate items
-// When passed to tally
-// Then it should return counts for each unique item
-
-// Given an invalid input like a string
-// When passed to tally
-// Then it should throw an error
+test("tally on an empty array returns an empty object", () => {
+  expect(() => tally("string")).toThrow("Invalid input!");
+});

Sprint-2/interpret/invert.js

@@ -1,29 +1,30 @@
-// Let's define how invert should work
-
-// Given an object
-// When invert is passed this object
-// Then it should swap the keys and values in the object
-
-// 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;
+    //invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
 // 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}
-
-// c) What does Object.entries return? Why is it needed in this program?
-
-// d) Explain why the current return value is different from the target output
-
-// e) Fix the implementation of invert (and write tests to prove it's fixed!)
+// {"1":"a", "2":"b"}
+// d) What does Object.entries return? Why is it needed in this program?
+//object.entries takes an objecet and returns an array of its key-value pairs.
+// e) Explain why the current return value is different from the target output
+//because we use .key notation we are setting a property named "key" on our Object.
+// f) Fix the implementation of invert (and write tests to prove it's fixed!)
+module.exports = invert;

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,9 @@
+const invert = require("./invert.js");
+
+test("swap key with value", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+});
+
+test("swap key with value", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+});