ZA|Innocent Niwatwine| Data-groups Sprint-2

Sprint-2/debug/address.js

@@ -1,4 +1,8 @@
 // Predict and explain first...
+//The code is trying to access address[0], but address is an object, can not be an array.
+//Objects use keys instead of numeric indices.
+//So address[0] is undefined, because there is no property with the key "0".
+
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
@@ -12,4 +16,4 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(`My house number is ${address.houseNumber}`);

Sprint-2/debug/author.js

@@ -1,5 +1,9 @@
 // Predict and explain first...
 
+//for...of is used with iterables like arrays and strings
+//objects are not iterables by default as it is seen in the code like author which is an object
+
+
 // 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 +15,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of object.values(author) {
   console.log(value);
 }

Sprint-2/debug/recipe.js

@@ -1,4 +1,5 @@
 // Predict and explain first...
+////${recipe} brings the entire object (recipe) directly into the string.
 
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
@@ -12,4 +13,4 @@ const recipe = {
 
 console.log(`${recipe.title} serves ${recipe.serves}
   ingredients:
-${recipe}`);
+  ${recipe.ingredients.join("\n")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,6 @@
-function contains() {}
+function contains(array, value) {
+    return array.includes(value);
+}
+
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -22,14 +22,32 @@ as the object doesn't contains a key of 'c'
 // Then it should return false
 test.todo("contains on empty object returns false");
 
+// Empty object return false
+test("contains on empty object returns false", () => {
+    const result = contains({}, "a");
+    expect(result).toBe(false); });
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
 
+// Object with properties and existing key should return true
+test("contains returns true for existing property", () => {
+  const obj = { a: 1, b: 2 };
+  const result = contains(obj, "a");
+  expect(result).toBe(true);
+});
+
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
-
+test("contains returns false for non-existing property", () => {
+  const obj = { a: 1, b: 2 };
+  const result = contains(obj, "c");
+  expect(result).toBe(false);
+});
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("contains returns false or throws when input is not an object", () => {
+    const obj = ["a", "b"];
+     expect(() => contains(["a", "b"], "a")).toThrow(); });

Sprint-2/implement/lookup.js

@@ -1,4 +1,12 @@
-function createLookup() {
+function createLookup(pairs) {
+    const lookup= {};
+   for (let [countryCode, currencyCode] of pairs) {
+      lookup[countryCode] = currencyCode;
+    }
+
+    return lookup;
+    // implementation here
+  }
   // implementation here
 }
 

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,18 @@
 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 input = [
+    ['US', 'USD'],
+    ['CA', 'CAD']
+  ];
+  const expected = {
+    US: 'USD',
+    CA: 'CAD'
+  };
+ expect(createLookup(input)).toEqual(expected);
+});
+
 
 /*
 

Sprint-2/implement/querystring.js

@@ -1,14 +1,18 @@
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
-    return queryParams;
-  }
+  if (!queryString) return queryParams;
+
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
-  }
+    const [key, ...rest] = pair.split("="); // Grab everything after first '='
+    const value = rest.join("="); // Safely join back if value had '=' signs
+
+    const decodedKey = decodeURIComponent((key || "").replace(/\+/g, " "));
+    const decodedValue = decodeURIComponent((value || "").replace(/\+/g, " "));
+
+     queryParams[decodedKey] = decodedValue;
+   }
 
   return queryParams;
 }

Sprint-2/implement/querystring.test.js

@@ -4,9 +4,31 @@
 // 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")
-
-test("parses querystring values containing =", () => {
-  expect(parseQueryString("equation=x=y+1")).toEqual({
+test("parses querystring values containing +", () => {
+  expect(parseQueryString("equation=x%3Dy%2B1")).toEqual({
     "equation": "x=y+1",
   });
+});
+  test("returns empty object for empty query string", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+test("parses single key with empty value", () => {
+  expect(parseQueryString("foo=")).toEqual({ foo: "" });
+});
+
+test("parses single key with no equals sign", () => {
+  expect(parseQueryString("foo")).toEqual({ foo: "" });
+});
+
+test("parses multiple key-value pairs", () => {
+  expect(parseQueryString("a=1&b=2")).toEqual({ a: "1", b: "2" });
+});
+
+test("decodes URL-encoded characters", () => {
+  expect(parseQueryString("name=John%20Doe&city=New%20York")).toEqual({
+    name: "John Doe",
+    city: "New York",
+
+  });
 });

Sprint-2/implement/tally.js

@@ -1,3 +1,22 @@
-function tally() {}
 
+function tally(items) {
+    // Validate input: must be an array
+    if (!Array.isArray(items)) {
+      throw new Error("Input must be an array");
+    }
+
+    // Create an object to hold counts
+    const counts = {};
+
+    // Loop through each item and count occurrences
+    for (const item of items) {
+      if (counts[item]) {
+        counts[item] += 1;
+      } else {
+        counts[item] = 1;
+      }
+    }
+
+    return counts;
+  }
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -23,12 +23,24 @@ 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");
+test("tally on an empty array returns an empty object", () => {
+    expect(tally([])).toEqual({});
+  });
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
 
+test("tally counts each unique item correctly", () => {
+    expect(tally(["a", "a", "b", "c"])).toEqual({
+      a: 2,
+      b: 1,
+      c: 1,
+    });
+  });
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("tally throws error on non-array input", () => {
+    expect(() => tally("not-an-array")).toThrow("Input must be an array");
+  });

Sprint-2/interpret/invert.js

@@ -10,20 +10,53 @@ function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
 // a) What is the current return value when invert is called with { a : 1 }
 
+// // { key: 1 }
+
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// { key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// { '1': 'a', '2': 'b' }
 
 // c) What does Object.entries return? Why is it needed in this program?
+// It returns an array of key-value pairs from the object obj, where each pair is itself an array 
 
 // d) Explain why the current return value is different from the target output
+// The return is inside the first loop, where the function will exit after the first iteration, and never processes all key-value pairs.
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+
+test("inverts an empty object to an empty object", () => {
+  expect(invert({})).toEqual({});
+});
+
+test("inverts an object with one key-value pair", () => {
+  expect(invert({ x: 10 })).toEqual({ "10": "x" });
+});
+
+test("inverts a simple object", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ "1": "a", "2": "b" });
+});
+
+test("inverts an object with duplicate values, keeping the last key", () => {
+  expect(invert({ a: 1, b: 1 })).toEqual({ "1": "b" });
+});
+
+test("inverts an object with string values", () => {
+  expect(invert({ hello: "world", name: "Innocent" })).toEqual({
+    world: "hello",
+    Innocent: "name",
+  });
+});
+
+test("throws an error when given a non-object input", () => {
+  expect(() => invert("not an object")).toThrow("Input must be an object");
+});