London|26-ITP-January|Alexandru Pocovnicu|Sprint 2|Data Groups

Sprint-2/debug/address.js

@@ -1,4 +1,6 @@
 // Predict and explain first...
+// it will print : My house number is undefined
+//objects aren't indexed
 
 // This code should log out the houseNumber from the address object
 // but it 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 +1,6 @@
 // Predict and explain first...
+//for...of works only on iterable data types
+// we will get an error
 
 // 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 +13,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
-  console.log(value);
+for (const key in author) {
+  console.log(author[key]);
 }

Sprint-2/debug/recipe.js

@@ -1,4 +1,8 @@
 // Predict and explain first...
+//this will log: bruschetta serves 2 ingredients: title: "bruschetta",
+  // serves: 2,
+  // ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
+//instead of the ingredients it prints the whole object again , also there is no \n 
 
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
@@ -10,6 +14,10 @@ const recipe = {
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+let ingredients=[]
+ for(let ingredient of recipe.ingredients){
+  ingredients.push(ingredient)
+ }
+  console.log(
+  `${recipe.title} serves ${recipe.serves} ingredients:\n${ingredients.join("\n")}`)
+

Sprint-2/implement/contains.js

@@ -1,3 +1,15 @@
-function contains() {}
+function contains(obj, propertyName) {
+  if (typeof obj !== "object" || obj === null || Array.isArray(obj)) {
+    throw new Error("Invalid object");
+  }
+  if (Object.keys(obj).length === 0) {
+    return false;
+  }
+  if (Object.keys(obj).includes(propertyName)) {
+    return true;
+  }
+  return false;
+}
+
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -20,16 +20,32 @@ 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("contains on empty object and propertyName='k' returns false", () => {
+  expect(contains({}, "k")).toEqual(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test(
+  "when contains is called with an object and an existing property name as arguments,it returns true ",()=>{
+    expect(contains({a:9},"a")).toEqual(true)
+  }
+);
+
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("when contains is called with an object and a non-existing property name as arguments,it returns false ", () => {
+  expect(contains({ a: 9,color:"pink",day:"Sunday" }, "John")).toEqual(false);
+});
+
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("when contains is called with the string 'parameter' and propertyName='a' as arguments it throws an error", () => {
+  expect(() => contains("parameter", "a")).toThrow("Invalid object");
+});
+

Sprint-2/implement/lookup.js

@@ -1,5 +1,19 @@
-function createLookup() {
-  // implementation here
+function createLookup(array) {
+  let object={}
+  for(let element of array){
+    let key=element[0]
+    let value=element[1]
+    object[key]=value
+  }
+  return object
 }
 
+console.log(
+  createLookup([
+    ["US", "USD"],
+    ["CA", "CAD"],
+  ])
+);
+
+
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,16 @@
 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,when createLookup is passed[['US', 'USD'], ['CA', 'CAD']] it returns {'US': 'USD','CA': 'CAD'}", () => {
+  expect(
+    createLookup([
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ])
+  ).toEqual({
+    US: "USD",
+    CA: "CAD",
+  });
+});
 
 /*
 

Sprint-2/implement/querystring.js

@@ -6,11 +6,18 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    const indexOfEqual = pair.indexOf("=");
+    if (indexOfEqual === -1) {
+      queryParams[pair] = "";
+    } else {
+      const key = [pair.slice(0, indexOfEqual)];
+      const value = pair.slice(indexOfEqual + 1);
+      queryParams[key] = value;
+    }
   }
 
   return queryParams;
 }
+console.log(parseQueryString("=equationtu"));
 
 module.exports = parseQueryString;

Sprint-2/implement/querystring.test.js

@@ -3,10 +3,25 @@
 // 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",
   });
 });
+
+test("parses multiple querystring divided by &", () => {
+  expect(parseQueryString("equation=x=y+1&color=blue")).toEqual({
+    equation: "x=y+1",
+    color: "blue",
+  });
+});
+
+test("it returns the value as an empty string if the querystring has no =", () => {
+  expect(parseQueryString("day")).toEqual({ day: "" });
+});
+
+test("it returns the key as an empty string if the querystring has no nothing before =", () => {
+  expect(parseQueryString("=day")).toEqual({ "": "day" });
+});

Sprint-2/implement/tally.js

@@ -1,3 +1,12 @@
-function tally() {}
+function tally(array) {
+  if (!Array.isArray(array)) {
+    throw new Error("Invalid input");
+  }
+  let obj = {};
+  array.forEach((elem) => {
+    obj[elem] = (obj[elem] || 0) + 1;
+  });
+  return obj;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -23,12 +23,20 @@ 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("when an empty array is passed to tally it 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("when an array with duplicate items is passed to tally , it returns counts for each unique item", () => {
+  expect(tally(["t", "d", 5, "t", 5])).toEqual({ t: 2, d: 1, 5: 2 });
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("when a string is passed to tally it throws error", () => {
+  expect(() => tally("asd")).toThrow("Invalid input");
+});

Sprint-2/interpret/invert.js

@@ -7,23 +7,32 @@
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
 function invert(obj) {
+  if (typeof obj !== "object" || Array.isArray(obj) || obj === null)
+    throw new Error("Invalid input");
   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 }
+//{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 the key:value pairs of obj,it's needed to extract those pairs from obj
 
 // d) Explain why the current return value is different from the target output
+//because it's using invertedObj.key = value; instead of invertedObj[value] = key;
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,20 @@
+const invert = require("./invert.js");
+test("when passed a string invert will throw error", () => {
+  expect(() => invert("asd")).toThrow("Invalid input");
+});
+
+test("when passed an empty object, invert returns an empty object", () => {
+  expect(invert({})).toEqual({});
+});
+
+test("when passed an  object containing one key:value pair, invert returns an  object containing value:key", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+});
+
+test("when passed an  object containing multiple key:value pairs, invert returns an  object containing value:key pairs", () => {
+  expect(invert({ a: 1, apple: "red", month: "September" })).toEqual({
+    1: "a",
+    red: "apple",
+    September: "month",
+  });
+});

Sprint-2/stretch/count-words.js

@@ -26,3 +26,15 @@
 
 3. Order the results to find out which word is the most common in the input
 */
+function countWords(string) {
+  const noPunctuation = string.replace(/[.,!?]/g,"");
+  const array = noPunctuation.toLowerCase().split(" ");
+
+
+  let object = {};
+  array.forEach((word) => {
+    object[word] = (object[word] || 0) + 1;
+  });
+  return Object.values(object).sort((a,b)=>b-a)/////?????? stuck on how to order it
+}
+console.log(countWords("You, and .me? and you me me"));

Sprint-2/stretch/mode.js

@@ -9,7 +9,12 @@
 // into smaller functions using the stages above
 
 function calculateMode(list) {
-  // track frequency of each value
+  let freqs = elementFrequency(list);
+
+  return maxFrequency(freqs);
+}
+
+function elementFrequency(list) {
   let freqs = new Map();
 
   for (let num of list) {
@@ -19,8 +24,10 @@ function calculateMode(list) {
 
     freqs.set(num, (freqs.get(num) || 0) + 1);
   }
+  return freqs;
+}
 
-  // Find the value with the highest frequency
+function maxFrequency(freqs) {
   let maxFreq = 0;
   let mode;
   for (let [num, freq] of freqs) {
@@ -29,8 +36,9 @@ function calculateMode(list) {
       maxFreq = freq;
     }
   }
-
   return maxFreq === 0 ? NaN : mode;
 }
 
+
+
 module.exports = calculateMode;

Sprint-2/stretch/mode.test.js

@@ -9,7 +9,7 @@ const calculateMode = require("./mode.js");
 // Example:
 // Given [2,4,1,2,3,2,1]
 // When calculateMode is called on [2,4,1,2,3,2,1]
-// Then it should return 2 */
+// Then it should return 2 */ 
 
 describe("calculateMode()", () => {
   test("returns the most frequent number in an array", () => {

Sprint-2/stretch/till.js

@@ -8,7 +8,10 @@ function totalTill(till) {
   let total = 0;
 
   for (const [coin, quantity] of Object.entries(till)) {
-    total += coin * quantity;
+    const coinWithOutTrailingP = coin.slice(0, -1);
+    const numberCoin = +coinWithOutTrailingP;
+
+    total += numberCoin * quantity;
   }
 
   return `£${total / 100}`;
@@ -21,11 +24,29 @@ const till = {
   "20p": 10,
 };
 const totalAmount = totalTill(till);
+console.log(totalAmount);
 
 // a) What is the target output when totalTill is called with the till object
+//£4.40
 
 // b) Why do we need to use Object.entries inside the for...of loop in this function?
+// to get the key value pairs
 
 // c) What does coin * quantity evaluate to inside the for...of loop?
+//NaN
 
 // d) Write a test for this function to check it works and then fix the implementation of totalTill
+// const till1 = {
+//   "1p": 10,
+//   "5p": 6,
+//   "50p": 4,
+//   "20p": 10,
+// };
+
+const currentOutput = totalTill(till);
+const expectedOutput = "£4.4";
+
+console.assert(
+  currentOutput === expectedOutput,
+  `Expected ${expectedOutput}, got ${currentOutput}`
+);