diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..66b62aecc 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,5 +1,10 @@
// Predict and explain first...
+// This outputs undefined because address[0] tries to access an object like an array.
+// Objects use property names, not numeric indices.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors
+
// This code should log out the houseNumber from the address object
// but it isn't working...
// Fix anything that isn't working
@@ -12,4 +17,5 @@ const address = {
postcode: "XYZ 123",
};
-console.log(`My house number is ${address[0]}`);
+// Fix: Dot notation accesses the property correctly
+console.log(`My house number is ${address.houseNumber}`);
diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..acf633799 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,10 @@
// Predict and explain first...
+// This throws a TypeError because plain objects cannot be used with for...of directly.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/values
+
// This program attempts to log out all the property values in the object.
// But it isn't working. Explain why first and then fix the problem
@@ -11,6 +16,7 @@ const author = {
alive: true,
};
-for (const value of author) {
+// Fix: Object.values() returns an array that can be looped over
+for (const value of Object.values(author)) {
console.log(value);
}
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..06de93d0d 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,11 @@
// Predict and explain first...
+// This outputs [object Object] because putting an object in a template string calls toString().
+// The default toString() for objects just returns "[object Object]".
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toString
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join
+
// This program should log out the title, how many it serves and the ingredients.
// Each ingredient should be logged on a new line
// How can you fix it?
@@ -10,6 +16,7 @@ const recipe = {
ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
};
+// Fix: Accesses each property directly and uses join() to format the ingredients
console.log(`${recipe.title} serves ${recipe.serves}
ingredients:
-${recipe}`);
+${recipe.ingredients.join("\n")}`);
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..6c0e188ca 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,16 @@
-function contains() {}
+// Checks if an object has a specific property.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwnProperty
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
+
+function contains(obj, propertyName) {
+ // Returns false for invalid inputs (null, arrays, or non-objects)
+ if (typeof obj !== "object" || obj === null || Array.isArray(obj)) {
+ return false;
+ }
+
+ return obj.hasOwnProperty(propertyName);
+}
module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..90b5e0a8a 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/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 +17,54 @@ 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
+// Returns true when the property exists
+test("contains returns true if the property exists", () => {
+ expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
+});
+
// Given an empty object
// When passed to contains
// Then it should return false
-test.todo("contains on empty object returns false");
+
+// An empty object has no properties
+test("contains returns false for an empty object", () => {
+ expect(contains({}, "a")).toBe(false);
+});
// Given an object with properties
// When passed to contains with an existing property name
// Then it should return true
+// Finds a named property in a typical object
+test("contains returns true for another property that exists", () => {
+ expect(contains({ name: "Lisa", age: 73 }, "name")).toBe(true);
+});
+
// Given an object with properties
-// When passed to contains with a non-existent property name
+// When passed to contains with a property name that does not exist
+// Then it should return false
+
+// Returns false for a missing property
+test("contains returns false for a property that does not exist", () => {
+ expect(contains({ name: "Leo", age: 19 }, "height")).toBe(false);
+});
+
+// Given an object
+// When passed to contains with a property that does not exist
// Then it should return false
+// Returns false for a property not in the object
+test("contains returns false when the property is not present", () => {
+ expect(contains({ a: 1, b: 2 }, "c")).toBe(false);
+});
+
// Given invalid parameters like an array
// When passed to contains
// Then it should return false or throw an error
+
+// Handles invalid inputs gracefully
+test("contains handles invalid parameters", () => {
+ expect(contains([], "a")).toBe(false);
+ expect(contains(null, "a")).toBe(false);
+ expect(contains(undefined, "a")).toBe(false);
+});
diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..fbef830f3 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,20 @@
-function createLookup() {
- // implementation here
+// Converts an array of pairs into a lookup object.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors#bracket_notation
+
+function createLookup(arrayOfPairs) {
+ const lookupObject = {};
+
+ for (const pair of arrayOfPairs) {
+ const key = pair[0];
+ const value = pair[1];
+
+ // Bracket notation allows using a variable as the property name
+ lookupObject[key] = value;
+ }
+
+ return lookupObject;
}
module.exports = createLookup;
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..2ca0a2a92 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/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 +31,18 @@ It should return:
'CA': 'CAD'
}
*/
+
+// Converts multiple pairs into a lookup object
+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);
+});
diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..3c8aaf6ce 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -1,12 +1,26 @@
+// Parses a query string into an object.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/indexOf
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice
+
function parseQueryString(queryString) {
const queryParams = {};
+
+ // Returns early if the string is empty
if (queryString.length === 0) {
return queryParams;
}
+
const keyValuePairs = queryString.split("&");
for (const pair of keyValuePairs) {
- const [key, value] = pair.split("=");
+ // Finds only the first "=" since values may contain "=" too
+ const firstEqualsIndex = pair.indexOf("=");
+
+ const key = pair.slice(0, firstEqualsIndex);
+ const value = pair.slice(firstEqualsIndex + 1);
+
queryParams[key] = value;
}
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 3e218b789..6b2c0fa51 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -3,10 +3,54 @@
// 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");
+// Handles values containing "="
test("parses querystring values containing =", () => {
expect(parseQueryString("equation=x=y+1")).toEqual({
- "equation": "x=y+1",
+ equation: "x=y+1",
+ });
+});
+
+// Parses a simple key-value pair
+test("parses a simple key-value pair", () => {
+ expect(parseQueryString("name=John")).toEqual({
+ name: "Samantha",
+ });
+});
+
+// Parses multiple pairs separated by "&"
+test("parses multiple key-value pairs", () => {
+ expect(parseQueryString("name=John&age=25")).toEqual({
+ name: "Samantha",
+ age: "33",
+ });
+});
+
+// Returns an empty object for an empty string
+test("returns an empty object for an empty string", () => {
+ expect(parseQueryString("")).toEqual({});
+});
+
+// Handles keys with empty values
+test("parses a key with no value after the equals sign", () => {
+ expect(parseQueryString("name=")).toEqual({
+ name: "",
+ });
+});
+
+// Preserves multiple "=" in values
+test("parses querystring with multiple = signs in value", () => {
+ expect(parseQueryString("formula=a=b=c")).toEqual({
+ formula: "a=b=c",
+ });
+});
+
+// Handles a mix of simple and complex values
+test("parses mixed simple and complex key-value pairs", () => {
+ expect(parseQueryString("name=John&equation=1+1=2&city=London")).toEqual({
+ name: "Samantha",
+ equation: "1+1=2",
+ city: "London",
});
});
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..a5a869dcd 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,30 @@
-function tally() {}
+// Counts how often each item appears in an array.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of
+
+function tally(arrayOfItems) {
+ // Checks the input is actually an array
+ const inputIsNotAnArray = !Array.isArray(arrayOfItems);
+
+ if (inputIsNotAnArray) {
+ throw new Error("Input must be an array");
+ }
+
+ const countObject = {};
+
+ for (const item of arrayOfItems) {
+ // If the item is already counted, add 1; otherwise start at 1
+ const itemAlreadyCounted = countObject[item] !== undefined;
+
+ if (itemAlreadyCounted) {
+ countObject[item] = countObject[item] + 1;
+ } else {
+ countObject[item] = 1;
+ }
+ }
+
+ return countObject;
+}
module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..fd4affadd 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -20,15 +20,74 @@ const tally = require("./tally.js");
// When passed an array of items
// Then it should return an object containing the count for each unique item
+// Counts a single item
+test("tally counts a single item in an array", () => {
+ const input = ["a"];
+
+ const expectedOutput = { a: 1 };
+
+ expect(tally(input)).toEqual(expectedOutput);
+});
+
+// Counts repeated items correctly
+test("tally counts multiple occurrences of the same item", () => {
+ const input = ["a", "a", "a"];
+
+ const expectedOutput = { a: 3 };
+
+ expect(tally(input)).toEqual(expectedOutput);
+});
+
+// Counts different items with varying frequencies
+test("tally counts different items with varying frequencies", () => {
+ const input = ["a", "a", "b", "c"];
+
+ const expectedOutput = { a: 2, b: 1, c: 1 };
+
+ expect(tally(input)).toEqual(expectedOutput);
+});
+
// 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");
+
+// Returns an empty object for an empty array
+test("tally on an empty array returns an empty object", () => {
+ const input = [];
+
+ const expectedOutput = {};
+
+ expect(tally(input)).toEqual(expectedOutput);
+});
// 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
+// Handles real-world data with duplicates
+test("tally handles an array with many duplicate items", () => {
+ const input = ["apple", "banana", "apple", "orange", "banana", "apple"];
+
+ const expectedOutput = { apple: 3, banana: 2, orange: 1 };
+
+ expect(tally(input)).toEqual(expectedOutput);
+});
+
+// Given invalid input like a string
// When passed to tally
// Then it should throw an error
+
+// Throws an error for a string input
+test("tally throws an error when given a string instead of an array", () => {
+ expect(() => tally("not an array")).toThrow("Input must be an array");
+});
+
+// Throws an error for null
+test("tally throws an error when given null", () => {
+ expect(() => tally(null)).toThrow("Input must be an array");
+});
+
+// Throws an error for undefined
+test("tally throws an error when given undefined", () => {
+ expect(() => tally(undefined)).toThrow("Input must be an array");
+});
diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..97b8bf749 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -6,24 +6,42 @@
// 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;
- }
-
- return invertedObj;
-}
+// Swaps the keys and values of an object.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors#bracket_notation
// a) What is the current return value when invert is called with { a : 1 }
+// { key: 1 } — the literal string "key" is used as the property name.
// b) What is the current return value when invert is called with { a: 1, b: 2 }
+// { key: 2 } — each iteration overwrites the same "key" property.
// c) What is the target return value when invert is called with {a : 1, b: 2}
+// { "1": "a", "2": "b" } — values become keys and keys become values.
// c) What does Object.entries return? Why is it needed in this program?
+// Object.entries returns an array of [key, value] pairs.
+// It is needed because for...of cannot iterate over plain objects directly.
// d) Explain why the current return value is different from the target output
+// The bug uses dot notation (invertedObj.key), which creates a literal property called "key".
+// Bracket notation (invertedObj[value]) uses the variable's value as the property name instead.
// e) Fix the implementation of invert (and write tests to prove it's fixed!)
+
+function invert(obj) {
+ const invertedObj = {};
+
+ for (const [key, value] of Object.entries(obj)) {
+ // Bracket notation allows using the value as a property name
+ invertedObj[value] = key;
+ }
+
+ return invertedObj;
+}
+
+// Testing the fix with console.log
+console.log(invert({ a: 1 })); // Expected: { "1": "a" }
+console.log(invert({ a: 1, b: 2 })); // Expected: { "1": "a", "2": "b" }
+console.log(invert({ x: 10, y: 20 })); // Expected: { "10": "x", "20": "y" }
diff --git a/Sprint-3/alarmclock/alarmclock.js b/Sprint-3/alarmclock/alarmclock.js
index 6ca81cd3b..a971aca5a 100644
--- a/Sprint-3/alarmclock/alarmclock.js
+++ b/Sprint-3/alarmclock/alarmclock.js
@@ -1,4 +1,54 @@
-function setAlarm() {}
+// Stores the interval ID to allow clearing the timer when needed
+let intervalId;
+
+// Reference: https://developer.mozilla.org/en-US/docs/Web/API/setInterval
+function setAlarm() {
+ const input = document.getElementById("alarmSet");
+ let totalSeconds = parseInt(input.value);
+
+ if (isNaN(totalSeconds) || totalSeconds < 0) {
+ alert("Please enter a valid positive number for the time.");
+ return;
+ }
+
+ // Prevents multiple timers from running simultaneously
+ if (intervalId) clearInterval(intervalId);
+
+ // Ensures a clean visual state before starting a new countdown
+ document.body.style.backgroundColor = "";
+
+ updateDisplay(totalSeconds);
+
+ intervalId = setInterval(() => {
+ totalSeconds--;
+ updateDisplay(totalSeconds);
+
+ if (totalSeconds <= 0) {
+ clearInterval(intervalId);
+ playAlarm();
+ document.body.style.backgroundColor = "#db4d4d";
+ }
+ }, 1000);
+}
+
+function updateDisplay(totalSeconds) {
+ const minutes = Math.floor(totalSeconds / 60);
+ const seconds = totalSeconds % 60;
+ const formattedMinutes = String(minutes).padStart(2, "0");
+ const formattedSeconds = String(seconds).padStart(2, "0");
+ document.getElementById(
+ "timeRemaining"
+ ).innerText = `Time Remaining: ${formattedMinutes}:${formattedSeconds}`;
+}
+
+// Resets the alarm state completely, allowing the user to set a new alarm
+// The setup() listener handles pausing the audio separately
+document.getElementById("stop").addEventListener("click", () => {
+ if (intervalId) clearInterval(intervalId);
+ document.body.style.backgroundColor = "";
+ document.getElementById("timeRemaining").innerText = "Time Remaining: 00:00";
+ document.getElementById("alarmSet").value = "";
+});
// DO NOT EDIT BELOW HERE
diff --git a/Sprint-3/alarmclock/index.html b/Sprint-3/alarmclock/index.html
index 48e2e80d9..ff2d3b453 100644
--- a/Sprint-3/alarmclock/index.html
+++ b/Sprint-3/alarmclock/index.html
@@ -4,7 +4,7 @@
- Title here
+ Alarm clock app
diff --git a/Sprint-3/quote-generator/index.html b/Sprint-3/quote-generator/index.html
index 30b434bcf..3feba441d 100644
--- a/Sprint-3/quote-generator/index.html
+++ b/Sprint-3/quote-generator/index.html
@@ -3,13 +3,21 @@
- Title here
+ Quote generator app
+
+
-