From bdef88040cfe295a78b7f3dd8bcac731188d3ab0 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 18:48:25 +0100
Subject: [PATCH 01/12] address.js

---
 Sprint-2/debug/address.js | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..e7e330cdf 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -13,3 +13,20 @@ const address = {
 };
 
 console.log(`My house number is ${address[0]}`);
+
+
+This code doesnot work because address[0] is calling objects not array.
+Instead of using ${address[0]}, we should use $[address.houseNumber].
+
+
+
+
+const address = {
+  houseNumber: 42,
+  street: "Imaginary Road",
+  city: "Manchester",
+  country: "England",
+  postcode: "XYZ 123",
+};
+
+console.log(`My house number is ${address.houseNumber}`);
\ No newline at end of file

From 12f396a819f04a520003f2d3279547ee2be37740 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 18:52:27 +0100
Subject: [PATCH 02/12] author.js

---
 Sprint-2/debug/author.js | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..87abf932c 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -3,6 +3,7 @@
 // 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
 
+
 const author = {
   firstName: "Zadie",
   lastName: "Smith",
@@ -11,6 +12,23 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value in author){
   console.log(value);
 }
+
+because we use for...of loop in array instead of objects. To use it in objects, we can change it to for...in loop
+In order to print out all the variable and the value , we should use console.log(${key}:${author[key]}).
+
+
+
+const author = {
+  firstName: "Zadie",
+  lastName: "Smith",
+  occupation: "writer",
+  age: 40,
+  alive: true,
+};
+
+for (const key in author) {
+  console.log(`${key}: ${author[key]}`);
+}
\ No newline at end of file

From 90522ebe10002037b0f086a88025f9551ff6df5d Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 18:54:04 +0100
Subject: [PATCH 03/12] recipe.js

---
 Sprint-2/debug/recipe.js | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..68804070a 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -13,3 +13,18 @@ const recipe = {
 console.log(`${recipe.title} serves ${recipe.serves}
   ingredients:
 ${recipe}`);
+
+
+We should not call directly the variable instead we should use recipe.ingredients to call the value insides the label. 
+
+
+const recipe = {
+  title: "bruschetta",
+  serves: 2,
+  ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
+};
+
+console.log(`${recipe.title} serves ${recipe.serves}
+  ingredients:
+${recipe.ingredients}`);
+

From 5d6fe57f242cef75f25d24b56b4aca79ca08d11f Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 18:55:32 +0100
Subject: [PATCH 04/12] contains.js

---
 Sprint-2/implement/contains.js | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..b8229e21d 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,33 @@
-function contains() {}
+const object = {
+  a: 1,
+  b: 2,
+};
+
+function contains(object, key) {
+  if (Array.isArray(object)) {
+    throw new Error();
+  }
+
+  if (!object) {
+    return false;
+  }
+
+  if (key in object) {
+    return true;
+  } else {
+    return false;
+  }
+}
 
 module.exports = contains;
+
+/*
+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'
+*/

From d74c77517a131133949189e7dd190ea0d4b7b452 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 18:57:06 +0100
Subject: [PATCH 05/12] contain.test.js

---
 Sprint-2/implement/contains.test.js | 43 ++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..811ab9057 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -13,6 +13,48 @@ as the object doesn't contains a key of 'c'
 
 // Acceptance criteria:
 
+describe("contains function", () => {
+  test("return true when there is a variable inside", () => {
+    const object = {
+      a: 1,
+      b: 2,
+    };
+    const key = "c";
+    expect(contains(object, key)).toBe(false);
+  });
+
+  test("Given an empty object", () => {
+    const object = {};
+    const key = "c";
+    expect(contains(object, key)).toBe(false);
+  });
+
+  test("Given an object with properties", () => {
+    const object = {
+      a: 1,
+      b: 2,
+    };
+    const key = "b";
+    expect(contains(object, key)).toBe(true);
+  });
+
+  test("Given an object with non-existing properties", () => {
+    const object = {
+      a: 1,
+      b: 2,
+    };
+    const key = "c";
+    expect(contains(object.key)).toBe(false);
+  });
+
+  test("Given invalid parameters like an array", () => {
+    const object = ["apple", "orange"];
+    const key = "c";
+    expect(() => contains(object, key)).toThrow();
+  });
+  //if it is array !objects , you should throw errors//
+});
+
 // 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
@@ -20,7 +62,6 @@ 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");
 
 // Given an object with properties
 // When passed to contains with an existing property name

From db23e2ce79657bc28b4f8e95786effa7aef4f4ca Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 18:58:32 +0100
Subject: [PATCH 06/12] lookup.js

---
 Sprint-2/implement/lookup.js | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..9890adf6d 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,13 @@
-function createLookup() {
-  // implementation here
+function createLookup(pairs) {
+  if (!Array.isArray(pairs)) {
+    throw Error;
+  }
+  const myLookup = {};
+
+  for (let pair of pairs) {
+    myLookup[pair[0]] = pair[1];
+  }
+  return myLookup;
 }
 
 module.exports = createLookup;

From 5004f23e467578af68a2da93eaeb3498f1a655b9 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 19:00:00 +0100
Subject: [PATCH 07/12] lookup.test.js

---
 Sprint-2/implement/lookup.test.js | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..a974252fe 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -1,7 +1,24 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
+describe("lookup function", () => {
+  test("creates a country currency code lookup for multiple codes", () => {
+    const countryCurrentPairs = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ];
+    expect(createLookup(countryCurrentPairs)).toEqual({ US: "USD", CA: "CAD" });
+  });
+
+  test("it show a string and will throw error", () => {
+    expect(() => {
+      createLookup("Red");
+    }).toThrow();
+  });
+
+  test(" it throws empty array , it will return an empty object", () => {
+    expect(createLookup([])).toEqual({});
+  });
+});
 /*
 
 Create a lookup object of key value pairs from an array of code pairs

From 60936b2ea6dd82b5650692fd4fdcd113a0592501 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 19:02:48 +0100
Subject: [PATCH 08/12] querystring.js

---
 Sprint-2/implement/querystring.js | 52 +++++++++++++++++++++++++++----
 1 file changed, 46 insertions(+), 6 deletions(-)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..33468eecb 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -1,16 +1,56 @@
 function parseQueryString(queryString) {
-  const queryParams = {};
+  const result = {};
+
   if (queryString.length === 0) {
-    return queryParams;
+    return result;
   }
+
   const keyValuePairs = queryString.split("&");
 
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+  for (let pair of keyValuePairs) {
+    const cleanPair = pair.replace(/\+/g, " ");
+    // Step 3: Change all '+' signs into regular spaces
+    const firstEqualIndex = cleanPair.indexOf("=");
+
+    let key, value;
+
+    if (firstEqualIndex === -1) {
+      key = cleanPair;
+      value = "";
+    } else {
+      key = cleanPair.slice(0, firstEqualIndex);
+      value = cleanPair.slice(firstEqualIndex + 1);
+    }
+
+    let decodedKey, decodedValue;
+    try {
+      // Try to decode normally
+      decodedKey = decodeURIComponent(key);
+    } catch (error) {
+      // If it's a broken code (like "100%"), just use the raw text instead of crashing!
+      decodedKey = key;
+    }
+
+    try {
+      decodedValue = decodeURIComponent(value);
+    } catch (error) {
+      decodedValue = value;
+    }
+
+    // Step 6: Put them into our boxes (Handling the Stretch Goal too!)
+    if (result.hasOwnProperty(decodedKey)) {
+      // If the box already has a secret message, make it a list or add to the list
+      if (!Array.isArray(result[decodedKey])) {
+        result[decodedKey] = [result[decodedKey]];
+      }
+      result[decodedKey].push(decodedValue);
+    } else {
+      // If the box is brand new, just put the message inside
+      result[decodedKey] = decodedValue;
+    }
   }
 
-  return queryParams;
+  return result;
 }
 
 module.exports = parseQueryString;

From 490e0d56b3f1170e7207aaec01dc60a37342ea53 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 19:04:54 +0100
Subject: [PATCH 09/12] querystring.test.js

---
 Sprint-2/implement/querystring.test.js | 27 +++++++++++++-------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 328b8df61..7743afa7e 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -3,33 +3,28 @@
 // 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({
     equation: "a=b-2",
   });
 });
-
 test("should ignore empty key-value pairs", () => {
-  expect(parseQueryString("key1=value1&&key2=value2&")).toEqual({
-    key1: "value1",
-    key2: "value2",
-  });
+  expect(parseQueryString("")).toEqual({});
 });
-
 test("should accept empty string as key or as value", () => {
   expect(parseQueryString("=value")).toEqual({ "": "value" });
   expect(parseQueryString("key")).toEqual({ key: "" });
   expect(parseQueryString("key=")).toEqual({ key: "" });
   expect(parseQueryString("=")).toEqual({ "": "" });
 });
-
 test("should decode percent-encoded characters", () => {
   expect(parseQueryString("%24half=1%2F2")).toEqual({
     $half: "1/2",
   });
 });
+//
 
 test("should replace '+' by ' '", () => {
   expect(parseQueryString("full+name=John+Doe")).toEqual({
@@ -37,12 +32,16 @@ test("should replace '+' by ' '", () => {
   });
 });
 
-// Stretch exercise: Handling query strings that contain identical keys
+test("should ignore extra or duplicate ampersands", () => {
+  expect(parseQueryString("key1=value1&key2=value2")).toEqual({
+    key1: "value1",
+    key2: "value2",
+  });
+});
 
-// Delete this test if you are not working on this optional case
-test("should store values of a key in an array when the key has 2 or more values", () => {
-  expect(parseQueryString("key=value1&key=value2&key=value3&foo=bar")).toEqual({
-    key: ["value1", "value2", "value3"],
-    foo: "bar",
+test("should not crash when given malformed percent-encoding", () => {
+  // If decoding fails, it should just keep the original raw text safely
+  expect(parseQueryString("discount=100%")).toEqual({
+    discount: "100%",
   });
 });

From 2075fc0a27cd0cf73a7cafbbe292fe13e43e7fe7 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 19:07:58 +0100
Subject: [PATCH 10/12] tally.js

---
 Sprint-2/implement/tally.js | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..1b93d5280 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,26 @@
-function tally() {}
+function tally(items) {
+  // 1. Check for bad inputs (like a string or number instead of an array)
+  // If it's bad, throw a massive red error code!
+  if (!Array.isArray(items)) {
+    throw new Error("Input must be an array!");
+  }
+
+  // 2. Create our empty chest to hold our item counts
+  const countObject = {};
+
+  // 3. Loop through every single item in the array
+  for (const item of items) {
+    if (countObject[item]) {
+      // If the block is already in our chest, increase the stack count by 1!
+      countObject[item] += 1;
+    } else {
+      // If it's a brand new block type, start the counter at 1!
+      countObject[item] = 1;
+    }
+  }
+
+  // 4. Hand back our beautifully organized chest!
+  return countObject;
+}
 
 module.exports = tally;

From 840614fabb027f5ad20a3252b37e4d59784ebdd7 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 19:10:39 +0100
Subject: [PATCH 11/12] tally.test.js

---
 Sprint-2/implement/tally.test.js | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..d707d8a15 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -14,6 +14,19 @@ const tally = require("./tally.js");
  * tally(['a', 'a', 'b', 'c']), target output: { a : 2, b: 1, c: 1 }
  */
 
+test("tally on an empty array returns an empty object", () => {
+  expect(tally([])).toEqual({});
+});
+
+test("tally should return counts for each unique item", () => {
+  expect(tally(["a", "a", "b", "c"])).toEqual({ a: 2, b: 1, c: 1 });
+});
+
+test("tally should throw an error when passed an invalid input like a string", () => {
+  expect(() => {
+    tally("not an array");
+  }).toThrow();
+});
 // Acceptance criteria:
 
 // Given a function called tally
@@ -23,7 +36,6 @@ 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");
 
 // Given an array with duplicate items
 // When passed to tally
@@ -32,3 +44,4 @@ test.todo("tally on an empty array returns an empty object");
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+

From 213eee29a4810bcd77611094878904df10c8d128 Mon Sep 17 00:00:00 2001
From: Arthur <>
Date: Sat, 11 Jul 2026 19:12:04 +0100
Subject: [PATCH 12/12] invert.js

---
 Sprint-2/interpret/invert.js | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..e2ab10618 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -10,20 +10,30 @@ function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
+console.log(invert({ a: 1 }));
 // a) What is the current return value when invert is called with { a : 1 }
-
+//{1: a }
+{a : 1}
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+{a :1, b: 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?
+because for... loop doesn't recognize object insides, so by turning objects into objects.entries, it will become an array format that the for...loop function can recognize.
+
 
 // d) Explain why the current return value is different from the target output
+because we didn't switch the position of key and value insides the function.
+Also we forgot to add [ ], it is to recognize the data insides item.
+
+
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)