From 0e5bd642d35c5e7aeddc546d3c8be1f0665f8f7f Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Wed, 26 Nov 2025 11:32:31 +0000
Subject: [PATCH 01/21] fix(debug): use dot notation for address.houseNumber
access
---
Sprint-2/debug/address.js | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..eb3a443e4 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,5 +1,12 @@
// Predict and explain first...
+// The code will likely output undefined.
+// This is because `address[0]` tries to access an object property using an array index.
+// However, `address` is an object, not an array. Objects use keys (property names) to access values.
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors#dot_notation
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors#bracket_notation
+
// This code should log out the houseNumber from the address object
// but it isn't working...
// Fix anything that isn't working
@@ -12,4 +19,8 @@ const address = {
postcode: "XYZ 123",
};
-console.log(`My house number is ${address[0]}`);
+// Access the property using dot notation or bracket notation with the key name:
+// - Dot notation: `address.houseNumber`
+// - Bracket notation: `address["houseNumber"]`
+
+console.log(`My house number is ${address.houseNumber}`);
From 420e2983d7de5859959fc6fdb63f043300648d52 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Wed, 26 Nov 2025 22:43:54 +0000
Subject: [PATCH 02/21] fix: resolve TypeError by using Object.values() to
iterate over author object properties
---
Sprint-2/debug/author.js | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..aacfca41e 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,11 @@
// Predict and explain first...
+// The code will throw a `TypeError` because `author` is a plain object, and plain objects are not iterable (cannot be used with `for...of`).
+// References:
+// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of#iterating_over_plain_objects
+// - 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 +17,7 @@ const author = {
alive: true,
};
-for (const value of author) {
+// Get an array of values to iterate over
+for (const value of Object.values(author)) {
console.log(value);
}
From 13ef0b997e5aac7d05846d0a9f570f4fe7e08386 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Wed, 26 Nov 2025 23:03:52 +0000
Subject: [PATCH 03/21] fix: correct ingredient logging in recipe.js to display
each ingredient on a new line
---
Sprint-2/debug/recipe.js | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..0e2e5573c 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,13 @@
// Predict and explain first...
+// The output will contain `[object Object]` instead of the ingredients list.
+// Interpolating an object `${recipe}` calls its `toString()` method.
+// The default `toString()` for objects 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 +18,8 @@ const recipe = {
ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
};
+
+// `join("\n")` converts the array into a single string with newlines between.
console.log(`${recipe.title} serves ${recipe.serves}
ingredients:
-${recipe}`);
+${recipe.ingredients.join("\n")}`);
From 5bd937e950c0bc610e2c7e9beff0f9671636f214 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Thu, 27 Nov 2025 00:29:04 +0000
Subject: [PATCH 04/21] feat: implement and test contains function for object
property checking
---
Sprint-2/implement/contains.js | 8 +++++++-
Sprint-2/implement/contains.test.js | 29 ++++++++++++++++++++++++++---
2 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..922f9a383 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,9 @@
-function contains() {}
+function contains(obj, propertyName) {
+ 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..440e5441e 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:
@@ -16,20 +16,43 @@ 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("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");
+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
+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
+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
+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
+test("contains handles invalid parameters", () => {
+ expect(contains([], "a")).toBe(false);
+ expect(contains(null, "a")).toBe(false);
+ expect(contains(undefined, "a")).toBe(false);
+});
From ad67bd746fbf88d9094056516cc4e1e2c1d6d691 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:31:57 +0000
Subject: [PATCH 05/21] fix: use dot notation to access object property
---
Sprint-2/debug/address.js | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index eb3a443e4..66b62aecc 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,11 +1,9 @@
// Predict and explain first...
-// The code will likely output undefined.
-// This is because `address[0]` tries to access an object property using an array index.
-// However, `address` is an object, not an array. Objects use keys (property names) to access values.
-// References:
-// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors#dot_notation
-// - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors#bracket_notation
+// 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...
@@ -19,8 +17,5 @@ const address = {
postcode: "XYZ 123",
};
-// Access the property using dot notation or bracket notation with the key name:
-// - Dot notation: `address.houseNumber`
-// - Bracket notation: `address["houseNumber"]`
-
+// Fix: Dot notation accesses the property correctly
console.log(`My house number is ${address.houseNumber}`);
From b5500ee45fc47f88c3d1250d2f4ba602eb7ade5c Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:36:01 +0000
Subject: [PATCH 06/21] fix: use Object.values() to iterate over object
---
Sprint-2/debug/author.js | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index aacfca41e..acf633799 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,11 +1,10 @@
// Predict and explain first...
-// The code will throw a `TypeError` because `author` is a plain object, and plain objects are not iterable (cannot be used with `for...of`).
+// 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#iterating_over_plain_objects
+// - 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
@@ -17,7 +16,7 @@ const author = {
alive: true,
};
-// Get an array of values to iterate over
+// Fix: Object.values() returns an array that can be looped over
for (const value of Object.values(author)) {
console.log(value);
}
From 8470b2242ea56d6ce1def8bbe8835e99afd1574c Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:36:47 +0000
Subject: [PATCH 07/21] fix: access properties directly and join array for
output
---
Sprint-2/debug/recipe.js | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 0e2e5573c..06de93d0d 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,13 +1,11 @@
// Predict and explain first...
-// The output will contain `[object Object]` instead of the ingredients list.
-// Interpolating an object `${recipe}` calls its `toString()` method.
-// The default `toString()` for objects returns `"[object Object]"`.
+// 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?
@@ -18,8 +16,7 @@ const recipe = {
ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
};
-
-// `join("\n")` converts the array into a single string with newlines between.
+// Fix: Accesses each property directly and uses join() to format the ingredients
console.log(`${recipe.title} serves ${recipe.serves}
ingredients:
${recipe.ingredients.join("\n")}`);
From a1d45f7ad6d753f877cee416e5300abc919e94f8 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:38:42 +0000
Subject: [PATCH 08/21] feat: implement contains function to check object
properties
---
Sprint-2/implement/contains.js | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index 922f9a383..6c0e188ca 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,4 +1,11 @@
+// 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;
}
From 160eb23916fa13404b01d8f70fec8d6c53c4dafa Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:39:26 +0000
Subject: [PATCH 09/21] test: add tests for contains function
---
Sprint-2/implement/contains.test.js | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 440e5441e..90b5e0a8a 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -16,6 +16,8 @@ as the object doesn't contain 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
+
+// Returns true when the property exists
test("contains returns true if the property exists", () => {
expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
});
@@ -23,6 +25,8 @@ test("contains returns true if the property exists", () => {
// Given an empty object
// When passed to contains
// Then it should return false
+
+// An empty object has no properties
test("contains returns false for an empty object", () => {
expect(contains({}, "a")).toBe(false);
});
@@ -30,6 +34,8 @@ test("contains returns false for an empty object", () => {
// 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);
});
@@ -37,6 +43,8 @@ test("contains returns true for another property that exists", () => {
// Given an object with properties
// 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);
});
@@ -44,6 +52,8 @@ test("contains returns false for a property that does not exist", () => {
// 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);
});
@@ -51,6 +61,8 @@ test("contains returns false when the property is not present", () => {
// 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);
From a32e08bcb395f7a8cc8c7f0900593e25e54f9371 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:40:26 +0000
Subject: [PATCH 10/21] feat: implement createLookup function for key-value
pairs
---
Sprint-2/implement/lookup.js | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
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;
From 22585d30e68052e6cc63328ea360db0c92f19b95 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:40:55 +0000
Subject: [PATCH 11/21] test: add tests for createLookup function
---
Sprint-2/implement/lookup.test.js | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
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);
+});
From 3812df85cc1cb01e1e87fd142e5f7590b3c84111 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:54:24 +0000
Subject: [PATCH 12/21] test: add tests for parseQueryString function
---
Sprint-2/implement/querystring.test.js | 48 ++++++++++++++++++++++++--
1 file changed, 46 insertions(+), 2 deletions(-)
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",
});
});
From fb98fcba8a0836a09c6ac57777242dc4dc41931a Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:55:40 +0000
Subject: [PATCH 13/21] feat: implement parseQueryString with indexOf for edge
cases
---
Sprint-2/implement/querystring.js | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
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;
}
From 1862d498341a257a715e950d68b0e0aee858e7a0 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:56:40 +0000
Subject: [PATCH 14/21] test: add tests for tally function
---
Sprint-2/implement/tally.test.js | 63 +++++++++++++++++++++++++++++++-
1 file changed, 61 insertions(+), 2 deletions(-)
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");
+});
From bd8a3dc41878ae2c94066ce1192b7be363998c27 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 00:57:07 +0000
Subject: [PATCH 15/21] feat: implement tally function to count array items
---
Sprint-2/implement/tally.js | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
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;
From 071d46c6fb0abd3b3665a8b3c72cde49b4211fb9 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 01:23:18 +0000
Subject: [PATCH 16/21] fix: use bracket notation to correctly invert object
keys and values
---
Sprint-2/interpret/invert.js | 36 +++++++++++++++++++++++++++---------
1 file changed, 27 insertions(+), 9 deletions(-)
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" }
From 7881920cddbf1e7dae662f25fd6ebc8b3952500b Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 07:57:23 +0000
Subject: [PATCH 17/21] feat(alarmclock): implement countdown timer with
setInterval
---
Sprint-3/alarmclock/alarmclock.js | 52 ++++++++++++++++++++++++++++++-
1 file changed, 51 insertions(+), 1 deletion(-)
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
From f3adf966a01d04c16770b54b5330715ab99ef3fd Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 07:57:23 +0000
Subject: [PATCH 18/21] fix(alarmclock): update page title to 'Alarm clock app'
---
Sprint-3/alarmclock/index.html | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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
From fbc7f3f5d0cf149d6b39a27b7ab8d09bd1b58f06 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 07:57:23 +0000
Subject: [PATCH 19/21] feat(quote-generator): implement random quote display
with auto-play
---
Sprint-3/quote-generator/script.js | 46 ++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
create mode 100644 Sprint-3/quote-generator/script.js
diff --git a/Sprint-3/quote-generator/script.js b/Sprint-3/quote-generator/script.js
new file mode 100644
index 000000000..3547eafdf
--- /dev/null
+++ b/Sprint-3/quote-generator/script.js
@@ -0,0 +1,46 @@
+const quoteElement = document.querySelector("#quote");
+const authorElement = document.querySelector("#author");
+const newQuoteButton = document.querySelector("#new-quote");
+const autoPlayToggle = document.querySelector("#auto-play-toggle");
+const autoPlayStatus = document.querySelector("#auto-play-status");
+
+// Stores the interval ID to allow stopping auto-play when toggled off
+let autoPlayInterval;
+
+// Displays a random quote from the quotes array
+function displayRandomQuote() {
+ const randomQuote = pickFromArray(quotes);
+ quoteElement.textContent = randomQuote.quote;
+ authorElement.textContent = randomQuote.author;
+}
+
+// Sets up the event listeners for the application
+function setup() {
+ displayRandomQuote();
+
+ newQuoteButton.addEventListener("click", displayRandomQuote);
+
+ autoPlayToggle.addEventListener("change", (event) => {
+ if (event.target.checked) {
+ startAutoPlay();
+ } else {
+ stopAutoPlay();
+ }
+ });
+}
+
+// Enables automatic quote rotation every 5 seconds for hands-free browsing
+// Reference: https://developer.mozilla.org/en-US/docs/Web/API/setInterval
+function startAutoPlay() {
+ autoPlayStatus.textContent = "(auto play is on)";
+ autoPlayInterval = setInterval(displayRandomQuote, 5000);
+}
+
+// Stops the automatic quote rotation when the user wants manual control
+function stopAutoPlay() {
+ autoPlayStatus.textContent = "";
+ clearInterval(autoPlayInterval);
+}
+
+// Initializes the application when the window loads
+window.addEventListener("load", setup);
From 69034a99850e262452faf299b4a5515d58539294 Mon Sep 17 00:00:00 2001
From: Tarawally <41825140+Tarawally@users.noreply.github.com>
Date: Sat, 29 Nov 2025 07:57:23 +0000
Subject: [PATCH 20/21] fix(quote-generator): update page title, heading and
add stylesheet
---
Sprint-3/quote-generator/index.html | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
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
+
+
-