From 020a638595ef4931883d64819bc35689bba29b22 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 16:15:30 +0000
Subject: [PATCH 01/14] used a dot notation

---
 Sprint-2/debug/address.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..36d2f865d 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -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}`);

From 00d78e48cede8e8ec6e9230617a5b587a6fa7df2 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 16:29:27 +0000
Subject: [PATCH 02/14] predicted and explained

---
 Sprint-2/debug/address.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 36d2f865d..073565223 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// After i run it will be undefined or throw an error because this is an object not an array to use the square bracket.
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working

From 106c8d55eff2e539fc276e33d92c6d0ddc0a70e3 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 16:32:19 +0000
Subject: [PATCH 03/14] changed it to  for in loop

---
 Sprint-2/debug/author.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..4aae5ece2 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// I would say we should use for in loop to log out every value of each key.
 // 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 +11,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value in author) {
   console.log(value);
 }

From 72464812a4a2dbb09e870cf98121f66772af4095 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 16:44:13 +0000
Subject: [PATCH 04/14] modified author.js

---
 Sprint-2/debug/author.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 4aae5ece2..8716c3acf 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-// I would say we should use for in loop to log out every value of each key.
+// Plain objects are not iterable so we have to use some of the built in object methods.
 // 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 +11,6 @@ const author = {
   alive: true,
 };
 
-for (const value in author) {
+for (const value of  Object.values (author)) {
   console.log(value);
 }

From f31c786d5a5819441c4dabb3bff04c486831129a Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 16:58:12 +0000
Subject: [PATCH 05/14] predicted nad fixed recipe.js

---
 Sprint-2/debug/recipe.js | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..5cab01a54 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// I think I have to use index to log out every ingredient as it is an array.
 // 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 +11,9 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
+  ingredients 
+  ${recipe.ingredients[0]}:
+  ${recipe.ingredients[1]}:
+  ${recipe.ingredients[2]}:
+  ${recipe.ingredients[3]}:
 ${recipe}`);

From 85c361c604f40c0f29c2cb5ea31c7e12171720d6 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 18:20:54 +0000
Subject: [PATCH 06/14] tested my tests

---
 Sprint-2/implement/contains.js      |  11 ++-
 Sprint-2/implement/contains.test.js |  35 ++++++--
 Sprint-2/package.json               |   1 +
 package.json                        | 127 ++++++++++++++++++++++++++++
 4 files changed, 168 insertions(+), 6 deletions(-)
 create mode 100644 package.json

diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..2160a0bf8 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,12 @@
-function contains() {}
+function contains(obj, key) {
+    
+    if(typeof obj !== object || obj === null || Array.isArray(obj)){
+        return false;
+    }
+
+        return obj.hasOwnProperty(key);
+    
+    
+}
 
 module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..063f46a06 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:
@@ -20,16 +20,41 @@ as the object doesn't contains a key of 'c'
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
+
+test.todo("contains an empty object returns false", () => {
+  expect(contains({}, "a")).toBe(false);
+});
+
+// Given invalid parameters like an array
+// When passed to contains
+// Then it should return false or throw an error
+
+test("contains array-like object,invalid object and null  returns false",() => {
+    expect(contains([], "a")).toBe(false);
+    expect(contains(123, "a")).toBe(false);
+    expect(contains(null, "a")).toBe(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("returns true for existent property", () => {
+    const obj = {a: 1, b: 2}
+    expect(contains("a")).toBe(true);   
+});
+
+
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("returns false for non existent properties", () => {
+    const obj1= {a: 1, b:2}
+    expect(contains("c")).toBe(false);
+});
+
+
+
+
+
 
-// Given invalid parameters like an array
-// When passed to contains
-// Then it should return false or throw an error
diff --git a/Sprint-2/package.json b/Sprint-2/package.json
index 80c16780f..6fb939824 100644
--- a/Sprint-2/package.json
+++ b/Sprint-2/package.json
@@ -6,6 +6,7 @@
   "scripts": {
     "test": "jest"
   },
+
   "keywords": [],
   "author": "",
   "license": "ISC",
diff --git a/package.json b/package.json
new file mode 100644
index 000000000..26a487990
--- /dev/null
+++ b/package.json
@@ -0,0 +1,127 @@
+{
+  "devDependencies": {
+    "jest": "^30.2.0",
+    "test": "^3.3.0"
+  },
+  "name": "module-data-groups",
+  "version": "1.0.0",
+  "description": "Like learning a musical instrument, programming requires daily practice.",
+  "main": "index.js",
+  "dependencies": {
+    "abort-controller": "^3.0.0",
+    "array-buffer-byte-length": "^1.0.2",
+    "arraybuffer.prototype.slice": "^1.0.4",
+    "async-function": "^1.0.0",
+    "available-typed-arrays": "^1.0.7",
+    "base64-js": "^1.5.1",
+    "buffer": "^6.0.3",
+    "call-bind": "^1.0.8",
+    "call-bind-apply-helpers": "^1.0.2",
+    "call-bound": "^1.0.4",
+    "data-view-buffer": "^1.0.2",
+    "data-view-byte-length": "^1.0.2",
+    "data-view-byte-offset": "^1.0.1",
+    "define-data-property": "^1.1.4",
+    "define-properties": "^1.2.1",
+    "dunder-proto": "^1.0.1",
+    "es-abstract": "^1.24.0",
+    "es-define-property": "^1.0.1",
+    "es-errors": "^1.3.0",
+    "es-object-atoms": "^1.1.1",
+    "es-set-tostringtag": "^2.1.0",
+    "es-to-primitive": "^1.3.0",
+    "event-target-shim": "^5.0.1",
+    "events": "^3.3.0",
+    "for-each": "^0.3.5",
+    "function-bind": "^1.1.2",
+    "function.prototype.name": "^1.1.8",
+    "functions-have-names": "^1.2.3",
+    "generator-function": "^2.0.1",
+    "get-intrinsic": "^1.3.0",
+    "get-proto": "^1.0.1",
+    "get-symbol-description": "^1.1.0",
+    "globalthis": "^1.0.4",
+    "gopd": "^1.2.0",
+    "has-bigints": "^1.1.0",
+    "has-property-descriptors": "^1.0.2",
+    "has-proto": "^1.2.0",
+    "has-symbols": "^1.1.0",
+    "has-tostringtag": "^1.0.2",
+    "hasown": "^2.0.2",
+    "ieee754": "^1.2.1",
+    "internal-slot": "^1.1.0",
+    "is-array-buffer": "^3.0.5",
+    "is-async-function": "^2.1.1",
+    "is-bigint": "^1.1.0",
+    "is-boolean-object": "^1.2.2",
+    "is-callable": "^1.2.7",
+    "is-data-view": "^1.0.2",
+    "is-date-object": "^1.1.0",
+    "is-finalizationregistry": "^1.1.1",
+    "is-generator-function": "^1.1.2",
+    "is-map": "^2.0.3",
+    "is-negative-zero": "^2.0.3",
+    "is-number-object": "^1.1.1",
+    "is-regex": "^1.2.1",
+    "is-set": "^2.0.3",
+    "is-shared-array-buffer": "^1.0.4",
+    "is-string": "^1.1.1",
+    "is-symbol": "^1.1.1",
+    "is-typed-array": "^1.1.15",
+    "is-weakmap": "^2.0.2",
+    "is-weakref": "^1.1.1",
+    "is-weakset": "^2.0.4",
+    "isarray": "^2.0.5",
+    "math-intrinsics": "^1.1.0",
+    "minimist": "^1.2.8",
+    "object-inspect": "^1.13.4",
+    "object-keys": "^1.1.1",
+    "object.assign": "^4.1.7",
+    "own-keys": "^1.0.1",
+    "possible-typed-array-names": "^1.1.0",
+    "process": "^0.11.10",
+    "readable-stream": "^4.7.0",
+    "reflect.getprototypeof": "^1.0.10",
+    "regexp.prototype.flags": "^1.5.4",
+    "safe-array-concat": "^1.1.3",
+    "safe-buffer": "^5.2.1",
+    "safe-push-apply": "^1.0.0",
+    "safe-regex-test": "^1.1.0",
+    "set-function-length": "^1.2.2",
+    "set-function-name": "^2.0.2",
+    "set-proto": "^1.0.0",
+    "side-channel": "^1.1.0",
+    "side-channel-list": "^1.0.0",
+    "side-channel-map": "^1.0.1",
+    "side-channel-weakmap": "^1.0.2",
+    "stop-iteration-iterator": "^1.1.0",
+    "string_decoder": "^1.3.0",
+    "string.prototype.replaceall": "^1.0.11",
+    "string.prototype.trim": "^1.2.10",
+    "string.prototype.trimend": "^1.0.9",
+    "string.prototype.trimstart": "^1.0.8",
+    "typed-array-buffer": "^1.0.3",
+    "typed-array-byte-length": "^1.0.3",
+    "typed-array-byte-offset": "^1.0.4",
+    "typed-array-length": "^1.0.7",
+    "unbox-primitive": "^1.1.0",
+    "which-boxed-primitive": "^1.1.1",
+    "which-builtin-type": "^1.2.1",
+    "which-collection": "^1.0.2",
+    "which-typed-array": "^1.1.19"
+  },
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/Fithi-Teklom/Module-Data-Groups.git"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "bugs": {
+    "url": "https://github.com/Fithi-Teklom/Module-Data-Groups/issues"
+  },
+  "homepage": "https://github.com/Fithi-Teklom/Module-Data-Groups#readme"
+}

From d8bb643e850bab48e09701f9612998d17608ec63 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 18:38:33 +0000
Subject: [PATCH 07/14] made some adjustments for the contains.test.js

---
 Sprint-2/implement/contains.js      | 2 +-
 Sprint-2/implement/contains.test.js | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index 2160a0bf8..e1161c79c 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,6 +1,6 @@
 function contains(obj, key) {
     
-    if(typeof obj !== object || obj === null || Array.isArray(obj)){
+    if(typeof obj !== "object" || obj === null || Array.isArray(obj)){
         return false;
     }
 
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 063f46a06..afb41a825 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -21,7 +21,7 @@ as the object doesn't contain a key of 'c'
 // When passed to contains
 // Then it should return false
 
-test.todo("contains an empty object returns false", () => {
+test("contains an empty object returns false", () => {
   expect(contains({}, "a")).toBe(false);
 });
 
@@ -40,7 +40,7 @@ test("contains array-like object,invalid object and null  returns false",() => {
 // Then it should return true
 test("returns true for existent property", () => {
     const obj = {a: 1, b: 2}
-    expect(contains("a")).toBe(true);   
+    expect(contains(obj, "a")).toBe(true);   
 });
 
 

From 9547061575d796c1fcfb81b4c30ad24aa9162294 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Sun, 30 Nov 2025 19:37:10 +0000
Subject: [PATCH 08/14] done lookup.test.js

---
 Sprint-2/implement/lookup.js      |  7 ++++++-
 Sprint-2/implement/lookup.test.js | 11 ++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..2173ee23e 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,10 @@
-function createLookup() {
+function createLookup(pairs) {
   // implementation here
+  const lookup = {};
+  for(const [countryCode, currencyCode]of pairs){
+    lookup[countryCode] = currencyCode;
+  }
+  return lookup;
 }
 
 module.exports = createLookup;
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..e4218acf0 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -1,6 +1,15 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
+test("creates a country currency code lookup for multiple codes", () => {
+    const countryCurrencyPairs = [['US', 'USD'], ['CA', 'CAD']];
+
+     const expected = {
+    US: 'USD',
+    CA: 'CAD',
+     }
+     expect(createLookup(countryCurrencyPairs)).toEqual(expected);
+});
+
 
 /*
 

From 89482b0369f299222b812b1235d37d9d63eb7cff Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Mon, 1 Dec 2025 18:17:30 +0000
Subject: [PATCH 09/14] tally.test.js is done

---
 Sprint-2/implement/querystring.js      | 11 ++++++++++-
 Sprint-2/implement/querystring.test.js | 22 +++++++++++++++++++++-
 Sprint-2/implement/tally.js            | 19 ++++++++++++++++++-
 Sprint-2/implement/tally.test.js       | 24 +++++++++++++++++++++++-
 Sprint-2/package.json                  |  2 ++
 5 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..4ea0244e9 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -6,11 +6,20 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+
+    const idx = pair.indexOf("=");
+   
+    if (idx === -1) {
+      // No '=' found, treat entire pair as key with empty value
+      queryParams[pair] = "";
+    } else {
+    const key = pair.substring(0, idx);
+      const value = pair.substring(idx + 1);
     queryParams[key] = value;
   }
 
   return queryParams;
 }
+}
 
 module.exports = parseQueryString;
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 3e218b789..8adc247e6 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -3,10 +3,30 @@
 // 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");
 
 test("parses querystring values containing =", () => {
   expect(parseQueryString("equation=x=y+1")).toEqual({
     "equation": "x=y+1",
   });
 });
+test("parses empty values", () =>{
+  expect(parseQueryString("a=&b=2")).toEqual({a:"",b:"2"})
+});
+
+test("parses containing =",() => {
+  expect(parseQueryString("equation=x=y+1")).toEqual({equation: "x=y+1"})
+});
+
+
+test("parses empty string", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+test("parses multiple pairs including empty value", () => {
+  expect(parseQueryString("a=1&b=&c=3")).toEqual({ a: "1", b: "", c: "3" });
+});
+
+test("parses repeated keys (last one wins)", () => {
+  expect(parseQueryString("a=1&a=2")).toEqual({ a: "2" });
+});
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..7603dbc78 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,20 @@
-function tally() {}
+function tally(items) {
+     if (!Array.isArray(items)) {
+    throw new Error("Input must be an array");
+  }
+
+  const result = {};
+
+  for (const item of items) {
+    if (result[item]) {
+      result[item] += 1;
+    } else {
+      result[item] = 1;
+    }
+  }
+
+  return result;
+
+}
 
 module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..d11937802 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -23,12 +23,34 @@ const tally = require("./tally.js");
 // 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");
 
+
+// Empty array → empty object
+test("tally on an empty array returns an empty object", () => {
+  expect(tally([])).toEqual({});
+});
+
+
+test("tally counts occurrences of items", () => {
+  expect(tally(["a", "a", "b", "c"])).toEqual({
+    a: 2,
+    b: 1,
+    c: 1
+  });
+});
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("tally works for a single repeated item", () => {
+  expect(tally(["x", "x", "x"])).toEqual({ x: 3 });
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("tally throws an error for invalid input", () => {
+  expect(() => tally("not an array")).toThrow("Input must be an array");
+});
+
+
+
diff --git a/Sprint-2/package.json b/Sprint-2/package.json
index 6fb939824..0f6db50ec 100644
--- a/Sprint-2/package.json
+++ b/Sprint-2/package.json
@@ -6,6 +6,7 @@
   "scripts": {
     "test": "jest"
   },
+  "type": "module",
 
   "keywords": [],
   "author": "",
@@ -13,4 +14,5 @@
   "devDependencies": {
     "jest": "^29.7.0"
   }
+
 }

From 1903cda9a662296c0acbdad8c2585160143ddb16 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Mon, 1 Dec 2025 22:24:45 +0000
Subject: [PATCH 10/14] created a test file for invert.js

---
 Sprint-2/interpret/invert.js      | 15 ++++++++++++++-
 Sprint-2/interpret/invert.test.js | 28 ++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 Sprint-2/interpret/invert.test.js

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..19d9953bb 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -7,23 +7,36 @@
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
 function invert(obj) {
+  if (typeof obj !== "object" || obj === null || Array.isArray(obj)) {
+    throw new Error("Input must be a non-null object");
+  }
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
+module.exports = invert
+
 // 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 }
+//Only the last value remains, so it returns:
+//{ key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// { "1": "a", "2": "b" }
 
 // c) What does Object.entries return? Why is it needed in this program?
+// as it is a built in method Object.entries returns an array of [key, value] pairs.
+//It is needed so we can loop through both keys and values easily.
 
 // d) Explain why the current return value is different from the target output
+//Because the code uses invertedObj.key (a literal property named "key") instead of using the variable key.
+//It overwrites the same property instead of swapping keys and values
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
new file mode 100644
index 000000000..5dea1191d
--- /dev/null
+++ b/Sprint-2/interpret/invert.test.js
@@ -0,0 +1,28 @@
+const invert = require("./invert");
+
+test("inverts a simple object", () => {
+  expect(invert({ a: 1 })).toEqual({ "1": "a" });
+});
+
+test("inverts multiple key/value pairs", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ "1": "a", "2": "b" });
+});
+
+test("inverts string values", () => {
+  expect(invert({ x: "apple", y: "banana" })).toEqual({
+    apple: "x",
+    banana: "y"
+  });
+});
+
+test("throws an error when input is not an object", () => {
+  expect(() => invert("not an object")).toThrow("Input must be a non-null object");
+});
+
+test("throws an error for null", () => {
+  expect(() => invert(null)).toThrow("Input must be a non-null object");
+});
+
+test("throws an error for arrays", () => {
+  expect(() => invert([1, 2, 3])).toThrow("Input must be a non-null object");
+});

From 57a03164ce4473bf3a352d14fcd7664af0b383e0 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Mon, 1 Dec 2025 22:34:31 +0000
Subject: [PATCH 11/14] modified count-words.js

---
 Sprint-2/stretch/count-words.js | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/Sprint-2/stretch/count-words.js b/Sprint-2/stretch/count-words.js
index 8e85d19d7..34d21e156 100644
--- a/Sprint-2/stretch/count-words.js
+++ b/Sprint-2/stretch/count-words.js
@@ -26,3 +26,33 @@
 
 3. Order the results to find out which word is the most common in the input
 */
+function countWords(str){
+ str = str.toLowerCase();
+
+  // 2. Remove punctuation (anything that is not a letter, number, or space)
+  str = str.replace(/[^\w\s]/g, '');
+
+  // 3. Split the string into words
+  const words = str.split(/\s+/);
+
+  // 4. Create an object to store word counts
+  const wordCounts = {};
+
+  // 5. Count each word
+  for (const word of words) {
+    if (word === '') continue; // skip empty strings (in case of multiple spaces)
+    if (wordCounts[word]) {
+      wordCounts[word] += 1;
+    } else {
+      wordCounts[word] = 1;
+    }
+  }
+
+  // 6. Optional: Sort by frequency (most common first)
+  const sortedWordCounts = Object.fromEntries(
+    Object.entries(wordCounts).sort((a, b) => b[1] - a[1])
+  );
+  return sortedWordCounts;
+};
+
+console.log(countWords("You and me, and you!"));
\ No newline at end of file

From 23fc4938b3a8ab3d09bb51a8ba3abf5cc83aba66 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Mon, 1 Dec 2025 23:05:09 +0000
Subject: [PATCH 12/14]  added a test file to the till.js

---
 Sprint-2/stretch/mode.js      | 21 ++++++++++++++-------
 Sprint-2/stretch/till.js      | 11 +++++++++--
 Sprint-2/stretch/till.test.js |  6 ++++++
 3 files changed, 29 insertions(+), 9 deletions(-)
 create mode 100644 Sprint-2/stretch/till.test.js

diff --git a/Sprint-2/stretch/mode.js b/Sprint-2/stretch/mode.js
index 3f7609d79..3b46e6ba7 100644
--- a/Sprint-2/stretch/mode.js
+++ b/Sprint-2/stretch/mode.js
@@ -8,29 +8,36 @@
 // refactor calculateMode by splitting up the code
 // into smaller functions using the stages above
 
-function calculateMode(list) {
-  // track frequency of each value
+
+function trackFrequencies(list) {
   let freqs = new Map();
 
   for (let num of list) {
-    if (typeof num !== "number") {
-      continue;
-    }
+    if (typeof num !== "number") continue;
 
     freqs.set(num, (freqs.get(num) || 0) + 1);
   }
 
-  // Find the value with the highest frequency
+  return freqs;
+}
+
+function findMode(freqs) {
   let maxFreq = 0;
   let mode;
+
   for (let [num, freq] of freqs) {
     if (freq > maxFreq) {
-      mode = num;
       maxFreq = freq;
+      mode = num;
     }
   }
 
   return maxFreq === 0 ? NaN : mode;
 }
 
+function calculateMode(list) {
+  const freqs = trackFrequencies(list);
+  return findMode(freqs);
+}
+
 module.exports = calculateMode;
diff --git a/Sprint-2/stretch/till.js b/Sprint-2/stretch/till.js
index 6a08532e7..f896aec44 100644
--- a/Sprint-2/stretch/till.js
+++ b/Sprint-2/stretch/till.js
@@ -8,10 +8,11 @@ function totalTill(till) {
   let total = 0;
 
   for (const [coin, quantity] of Object.entries(till)) {
-    total += coin * quantity;
+     const value = parseInt(coin);
+    total += value * quantity;
   }
 
-  return `£${total / 100}`;
+  return `£${(total / 100).toFixed(2)}`;
 }
 
 const till = {
@@ -22,10 +23,16 @@ const till = {
 };
 const totalAmount = totalTill(till);
 
+module.exports = totalTill;
+
 // a) What is the target output when totalTill is called with the till object
+//£4.10
 
 // b) Why do we need to use Object.entries inside the for...of loop in this function?
+//Because Object.entries gives you both the coin and the quantity(which means key and value at once) in each loop.
 
 // c) What does coin * quantity evaluate to inside the for...of loop?
+//"1p" * 10 → NaN, because "1p" is not a number.
 
 // d) Write a test for this function to check it works and then fix the implementation of totalTill
+//the test is on another file.
\ No newline at end of file
diff --git a/Sprint-2/stretch/till.test.js b/Sprint-2/stretch/till.test.js
new file mode 100644
index 000000000..389347a47
--- /dev/null
+++ b/Sprint-2/stretch/till.test.js
@@ -0,0 +1,6 @@
+const totalTill = require("./totalTill");
+
+test("calculates the total in pounds", () => {
+  const till = { "1p": 10, "5p": 6, "50p": 4, "20p": 10 };
+  expect(totalTill(till)).toBe("£4.40");
+});

From d0281fd58225cedde7e14d694bcb3963d40ba63e Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Mon, 1 Dec 2025 23:13:21 +0000
Subject: [PATCH 13/14] test file has passed for till.js

---
 Sprint-2/stretch/till.js      | 1 +
 Sprint-2/stretch/till.test.js | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/stretch/till.js b/Sprint-2/stretch/till.js
index f896aec44..397a8efdc 100644
--- a/Sprint-2/stretch/till.js
+++ b/Sprint-2/stretch/till.js
@@ -22,6 +22,7 @@ const till = {
   "20p": 10,
 };
 const totalAmount = totalTill(till);
+console.log(totalAmount);
 
 module.exports = totalTill;
 
diff --git a/Sprint-2/stretch/till.test.js b/Sprint-2/stretch/till.test.js
index 389347a47..8e3c5f60a 100644
--- a/Sprint-2/stretch/till.test.js
+++ b/Sprint-2/stretch/till.test.js
@@ -1,6 +1,6 @@
-const totalTill = require("./totalTill");
+const totalTill = require("./till");
 
 test("calculates the total in pounds", () => {
   const till = { "1p": 10, "5p": 6, "50p": 4, "20p": 10 };
   expect(totalTill(till)).toBe("£4.40");
-});
+}); 

From 6d3cd1ab5ba8b3c47dbcc589a8e8ec10ffb5d825 Mon Sep 17 00:00:00 2001
From: Fithi Teklom <fthiteklom@gmail.com>
Date: Mon, 1 Dec 2025 23:23:58 +0000
Subject: [PATCH 14/14] modified querystring.js

---
 Sprint-2/implement/querystring.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 4ea0244e9..ce7b9174b 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -17,9 +17,8 @@ function parseQueryString(queryString) {
       const value = pair.substring(idx + 1);
     queryParams[key] = value;
   }
-
-  return queryParams;
 }
+return queryParams;
 }
 
 module.exports = parseQueryString;