Cape Town | 26-ITP-Sept | Leigh Ross | Sprint 2 | Coursework sprint 2

Sprint-2/debug/address.js

@@ -1,5 +1,16 @@
 // Predict and explain first...
+/*
+Predict
+The function is calling index 0 but there is not an index 0
+Console.log will show a ref error
+To fix this we need to change the index to [houseNumber]
 
+What actually happened
+Console.log showed undefined for that index
+Changed index to [houseNumber] this gave us a ref err 
+Therefore it must be address.houseNumber
+This works
+*/
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -12,4 +23,4 @@ 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 +1,11 @@
 // Predict and explain first...
-
+/*
+Predict
+for of loops work on iteration and we cant iterate objects
+To fix this we use for in loop 
+This loops over the keys
+Now we can use author[value] to get values
+*/
 // 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 +17,6 @@ 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

@@ -1,5 +1,9 @@
 // Predict and explain first...
-
+/*
+The ${recipe}`); line does not call the object correctly and shows [object Object]
+This is because it tries to convert the whole object to a string but it doesnt know how to display the information
+to fix this i used a for loop and iterated through the ingredients key's array to print each ingredient on a new line
+*/
 // 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 +15,9 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ingredients: `)
+
+for (let i=0; i < recipe.ingredients.length; i++) {
+  console.log(`${recipe.ingredients[i]}`)
+}
+

Sprint-2/implement/contains.js

@@ -1,3 +1,11 @@
-function contains() {}
-
+function contains(input, key) {
+    if (input === null || typeof input !== "object") {
+        throw new Error("contains requires an object")
+    } else {for (const keys in input){
+        if (keys === key) {
+            return true
+        }
+    }} return false
+}
+console.log(contains({a: 1}, 'a'))
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -23,18 +23,40 @@ as an array isn't an object
 // 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 returns false", () => {
+    const input = {};
+    const key = 'a'
+    const result = contains(input, key);
+    expect(result).toEqual(false)
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("given: object with keys and values & key within object returns true", () => {
+    const input = {a: 1, b: 2, c: 3};
+    const key = 'a'
+    const result = contains(input, key);
+    expect(result).toEqual(true)
+});
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("given: object with keys and values & key not within object returns true", () => {
+    const input = {a: 1, b: 2, c: 3};
+    const key = 'k'
+    const result = contains(input, key);
+    expect(result).toEqual(false)
+});
 
 // Given a value that isn't an object - an array, a string, a number,
 // null, or no argument at all
 // When passed to contains
 // Then it should throw Error("contains requires an object")
 // (careful: typeof [] and typeof null are both "object")
+test("given: value that is not an object throws error: 'contains requires an object'", () => {
+    const input = "tooth";
+    const key = 'k'
+    expect(() => contains(input, key)).toThrow("contains requires an object")
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,6 @@
-function createLookup() {
-  // implementation here
+function createLookup(input) {
+  return Object.fromEntries(input)
+
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,13 @@
 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 result = createLookup(input)
+  expect(result).toEqual({
+    'US': 'USD',
+    'CA': 'CAD'
+  })
+});
 
 /*
 

Sprint-2/implement/querystring.js

@@ -4,12 +4,27 @@ function parseQueryString(queryString) {
     return queryParams;
   }
   const keyValuePairs = queryString.split("&");
-
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+  let keyValuePair = keyValuePairs;
+  if (queryString.includes("+")) {
+    keyValuePair = keyValuePairs.map((keyValuePair) =>
+      keyValuePair.replaceAll("+", " ")
+    );
+  } else if(queryString.includes("%")) {
+    keyValuePair = keyValuePairs.map((keyValuePair) =>
+      decodeURIComponent(keyValuePair))
+  }; 
+
+  for (const pair of keyValuePair) {
+    if (pair === "") continue;
+    const eqIndex = pair.indexOf("=");
+    if (eqIndex === -1) {
+      queryParams[pair] = "";
+    } else {
+      const key = pair.slice(0, eqIndex);
+      const value = pair.slice(eqIndex + 1);
+      queryParams[key] = value;
+    }
   }
-
   return queryParams;
 }
 

Sprint-2/implement/querystring.test.js

@@ -40,9 +40,9 @@ test("should replace '+' by ' '", () => {
 // Stretch exercise: Handling query strings that contain identical keys
 
 // 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 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",
+//   });
+// });

Sprint-2/implement/tally.js

@@ -1,3 +1,16 @@
-function tally() {}
+function tally(array) {
+    if (!Array.isArray(array)){
+        throw new Error('tally requires an array')
+    }
+    const result = {};
+    for (const item of array){
+        if (Object.hasOwn(result, item)) {
+            result[item] = result[item] + 1
+        } else {
+            result[item] = 1
+        }
+    }
+    return result
+}
 
 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", () => {
+    const input = [];
+    const result = tally(input);
+    expect(result).toEqual({});
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("given array with duplicate items, return object with counts for each unique item", () => {
+    const input = ['a', 'a', 'b', 'c', 'c', 'c'];
+    const result = tally(input);
+    expect(result).toEqual({a: 2, b: 1, c: 3})
+})
 
 // Given an invalid input like a string, a number, or no argument at all
 // When passed to tally
 // Then it should throw Error("tally requires an array")
+test("given invalid input (str, num, no arg), throw error: 'tally requires an array'", () => {
+    expect(() => tally('meaf')).toThrow('tally requires an array')
+})

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"){
+    throw new Error('invert requires an object.')
+  }
   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 }
+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 }
+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}
+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?
+c) What does Object.entries return? Why is it needed in this program?
+It returns an array of key value pairs from the object.
+It is needed because we cannot iterate over objects with for..of. We convert the obj to array (key-value pairs) using Object.entries and then we can iterate.
 
-// d) Explain why the current return value is different from the target output
+d) Explain why the current return value is different from the target output
+We dont swop the key value pairs after they are in array form, we only place them back into the object as they were before.
+invertedObj also returns uses key as a property name, not a placeholder. When we call the function key is overwritten with more than one key-value pair as well so only the last k-v pair shows but with "key" as the key name.
 
-// e) Fix the implementation of invert (and write tests to prove it's fixed!)
+e) Fix the implementation of invert (and write tests to prove it's fixed!)
+*/

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,21 @@
+const invert = require("./invert.js");
+
+test("object with 1 key-value pair. returns object with key-value pairs swopped.", () => {
+  expect(invert({a: 1})).toEqual({'1': 'a'})
+})
+
+test("object with 2 key-value pairs. returns object with key-value pairs swopped.", () => {
+  expect(invert({a: 1, b: 2})).toEqual({'1': 'a', '2': 'b'})
+})
+
+test("object with 3 key-value pairs. returns object with key-value pairs swopped.", () => {
+  expect(invert({a: 1, b: 2, z: 12})).toEqual({'1': 'a', '2': 'b', '12': 'z'})
+})
+
+test("object with 0 key-value pair. returns empty object.", () => {
+  expect(invert({})).toEqual({})
+})
+
+test("object with invalid input. throw error: 'invert requires an object.", () => {
+  expect(() => invert("bones")).toThrow('invert requires an object.')
+})