BIRMINGHAM | ITP 26 JAN | Merve Reis | Sprint 2 | Module Data Groups

Sprint-2/debug/address.js

@@ -1,5 +1,7 @@
 // Predict and explain first...
 
+// Adress is not an array its an object, objects use key values so [0] is an array not a key value for a houseNumber.
+
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -12,4 +14,4 @@ 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

@@ -1,4 +1,5 @@
 // Predict and explain first...
+//The code fails because:for...of only works with iterable objects,Plain JavaScript objects,which is author here,are not iterable.
 
 // 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 +12,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
 }

Sprint-2/debug/recipe.js

@@ -11,5 +11,5 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ingredients:
+${recipe.ingredients.join("\n")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,9 @@
-function contains() {}
+function contains(obj, prop) {
+  if (obj === null || typeof obj !== "object" || Array.isArray(obj)) {
+    return false;
+  }
+
+  return Object.hasOwn(obj, prop);
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -1,35 +1,28 @@
 const contains = require("./contains.js");
 
-/*
-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'
-*/
-
-// Acceptance criteria:
-
-// 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
-
-// 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
-// Then it should return true
-
-// Given an object with properties
-// When passed to contains with a non-existent property name
-// Then it should return false
-
-// Given invalid parameters like an array
-// When passed to contains
-// Then it should return false or throw an error
+describe("contains", () => {
+  test("returns false for an empty object", () => {
+    expect(contains({}, "a")).toBe(false);
+  });
+
+  test("returns true when object contains the property", () => {
+    expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
+  });
+
+  test("returns false when object does not contain the property", () => {
+    expect(contains({ a: 1, b: 2 }, "c")).toBe(false);
+  });
+
+  test("returns false when given an array instead of an object", () => {
+    expect(contains([1, 2, 3], "0")).toBe(false);
+  });
+
+  test("returns false when given null", () => {
+    expect(contains(null, "a")).toBe(false);
+  });
+
+  test("returns false when given a non-object type", () => {
+    expect(contains(42, "a")).toBe(false);
+    expect(contains("string", "a")).toBe(false);
+  });
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,18 @@
-function createLookup() {
-  // implementation here
+function createLookup(pairs) {
+  if (!Array.isArray(pairs)) {
+    return {};
+  }
+
+  const lookup = {};
+
+  for (const pair of pairs) {
+    if (Array.isArray(pair) && pair.length === 2) {
+      const [country, currency] = pair;
+      lookup[country] = currency;
+    }
+  }
+
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,60 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
+describe("createLookup", () => {
+  test("creates a country currency code lookup for multiple codes", () => {
+    const input = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ];
+    const result = createLookup(input);
+
+    expect(result).toEqual({
+      US: "USD",
+      CA: "CAD",
+    });
+  });
+
+  test("returns empty object for empty array", () => {
+    expect(createLookup([])).toEqual({});
+  });
+
+  test("handles a single pair", () => {
+    const input = [["GB", "GBP"]];
+    expect(createLookup(input)).toEqual({
+      GB: "GBP",
+    });
+  });
+
+  test("ignores invalid pairs (not arrays)", () => {
+    const input = [["US", "USD"], "invalid", null];
+    expect(createLookup(input)).toEqual({
+      US: "USD",
+    });
+  });
+
+  test("ignores pairs that do not have exactly two elements", () => {
+    const input = [["US", "USD"], ["CA"], ["MX", "MXN", "extra"]];
+    expect(createLookup(input)).toEqual({
+      US: "USD",
+    });
+  });
+
+  test("overwrites duplicate country codes with the latest value", () => {
+    const input = [
+      ["US", "USD"],
+      ["US", "USN"],
+    ];
+    expect(createLookup(input)).toEqual({
+      US: "USN",
+    });
+  });
+
+  test("returns empty object for invalid input (not an array)", () => {
+    expect(createLookup(null)).toEqual({});
+    expect(createLookup({})).toEqual({});
+    expect(createLookup("string")).toEqual({});
+  });
+});
 
 /*
 
@@ -21,6 +75,7 @@ Then
  - The values are the corresponding currency codes
 
 Example
+
 Given: [['US', 'USD'], ['CA', 'CAD']]
 
 When

Sprint-2/implement/querystring.js

@@ -1,16 +1,34 @@
+
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
+
+  if (!queryString || typeof queryString !== "string") {
     return queryParams;
   }
+
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    if (!pair) continue;
+
+    const index = pair.indexOf("=");
+
+    let key, value;
+
+    if (index === -1) {
+      key = pair;
+      value = "";
+    } else {
+      key = pair.slice(0, index);
+      value = pair.slice(index + 1);
+    }
+
+    if (key) {
+      queryParams[key] = value;
+    }
   }
 
   return queryParams;
 }
 
-module.exports = parseQueryString;
+module.exports = parseQueryString;

Sprint-2/implement/querystring.test.js

@@ -3,10 +3,59 @@
 // 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",
+    equation: "x=y+1",
+  });
+});
+
+describe("parseQueryString edge cases", () => {
+  test("returns empty object for empty string", () => {
+    expect(parseQueryString("")).toEqual({});
+  });
+
+  test("handles multiple key value pairs", () => {
+    expect(parseQueryString("a=1&b=2")).toEqual({
+      a: "1",
+      b: "2",
+    });
+  });
+
+  test("handles missing value", () => {
+    expect(parseQueryString("a=")).toEqual({
+      a: "",
+    });
+  });
+
+  test("handles missing equals sign", () => {
+    expect(parseQueryString("a")).toEqual({
+      a: "",
+    });
+  });
+
+  test("handles multiple equals signs in value", () => {
+    expect(parseQueryString("a=1=2=3")).toEqual({
+      a: "1=2=3",
+    });
+  });
+
+  test("ignores empty pairs", () => {
+    expect(parseQueryString("a=1&&b=2")).toEqual({
+      a: "1",
+      b: "2",
+    });
+  });
+
+  test("overwrites duplicate keys with last value", () => {
+    expect(parseQueryString("a=1&a=2")).toEqual({
+      a: "2",
+    });
+  });
+
+  test("returns empty object for invalid input", () => {
+    expect(parseQueryString(null)).toEqual({});
+    expect(parseQueryString(undefined)).toEqual({});
   });
 });

Sprint-2/implement/tally.js

@@ -1,3 +1,15 @@
-function tally() {}
+function tally(items) {
+  if (!Array.isArray(items)) {
+    throw new Error("Input must be an array");
+  }
+
+  const counts = Object.create(null);
+
+  for (const item of items) {
+    counts[item] = (counts[item] || 0) + 1;
+  }
+
+  return counts;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -1,34 +1,31 @@
 const tally = require("./tally.js");
 
-/**
- * tally array
- *
- * In this task, you'll need to implement a function called tally
- * that will take a list of items and count the frequency of each item
- * in an array
- *
- * For example:
- *
- * tally(['a']), target output: { a: 1 }
- * tally(['a', 'a', 'a']), target output: { a: 3 }
- * tally(['a', 'a', 'b', 'c']), target output: { a : 2, b: 1, c: 1 }
- */
+describe("tally", () => {
+  test("tally on an empty array returns an empty object", () => {
+    expect(tally([])).toEqual({});
+  });
 
-// Acceptance criteria:
+  test("counts duplicate items correctly", () => {
+    expect(tally(["a", "a", "b", "c"])).toEqual({
+      a: 2,
+      b: 1,
+      c: 1,
+    });
+  });
 
-// Given a function called tally
-// When passed an array of items
-// Then it should return an object containing the count for each unique item
+  test("counts single item array", () => {
+    expect(tally(["a"])).toEqual({ a: 1 });
+  });
 
-// 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("counts all same items", () => {
+    expect(tally(["a", "a", "a"])).toEqual({ a: 3 });
+  });
 
-// Given an array with duplicate items
-// When passed to tally
-// Then it should return counts for each unique item
+  test("throws error for invalid input (string)", () => {
+    expect(() => tally("abc")).toThrow("Input must be an array");
+  });
 
-// Given an invalid input like a string
-// When passed to tally
-// Then it should throw an error
+  test("throws error for invalid input (null)", () => {
+    expect(() => tally(null)).toThrow("Input must be an array");
+  });
+});