London | 26-ITP-May | Mandip Sanger | Sprint 2 | Coursework

Sprint-2/debug/address.js

@@ -12,4 +12,4 @@ 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

@@ -11,6 +11,6 @@ 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

@@ -12,4 +12,4 @@ const recipe = {
 
 console.log(`${recipe.title} serves ${recipe.serves}
  ingredients:
-${recipe}`);
+${recipe.ingredients}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,19 @@
-function contains() {}
+function contains(object, property) {
+ if (object === null || typeof object !== "object" || Array.isArray(object)) {
+ return false;
+ }
+
+ return object.hasOwnProperty(property);
+}
 
 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'
+// */

Sprint-2/implement/contains.test.js

@@ -20,7 +20,6 @@ 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
@@ -33,3 +32,53 @@ test.todo("contains on empty object returns false");
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+
+// Given an empty object
+// When passed to contains
+// Then it should return false
+test("returns false for an empty object", () => {
+ expect(contains({}, "a")).toEqual(false);
+});
+
+// Given an object with properties
+// When passed to contains with an existing property name
+// Then it should return true
+test("returns true when the property exists", () => {
+ expect(contains({ a: 1, b: 2 }, "a")).toEqual(true);
+ expect(contains({ a: 1, b: 2 }, "b")).toEqual(true);
+});
+
+// Given an object with properties
+// When passed to contains with a non-existent property name
+// Then it should return false
+test("returns false when the property does not exist", () => {
+ expect(contains({ a: 1, b: 2 }, "c")).toEqual(false);
+});
+
+// Given an object with several properties
+// When checking another existing property
+// Then it should return true
+test("returns true for another existing property", () => {
+ expect(contains({ name: "Alice", age: 25 }, "age")).toEqual(true);
+});
+
+// Given an array
+// When passed to contains
+// Then it should return false
+test("returns false when given an array", () => {
+ expect(contains([1, 2, 3], "0")).toEqual(false);
+});
+
+// Given a null value
+// When passed to contains
+// Then it should return false
+test("returns false when given null", () => {
+ expect(contains(null, "a")).toEqual(false);
+});
+
+// Given an undefined value
+// When passed to contains
+// Then it should return false
+test("returns false when given undefined", () => {
+ expect(contains(undefined, "a")).toEqual(false);
+});

Sprint-2/implement/querystring.js

@@ -1,12 +1,31 @@
 function parseQueryString(queryString) {
  const queryParams = {};
+ if (queryString === "") {
+ return queryString;
+ }
  if (queryString.length === 0) {
  return queryParams;
  }
- const keyValuePairs = queryString.split("&");
+
+ const keyValuePairs = queryString.split("&").filter((pair) => pair !== "");
 
  for (const pair of keyValuePairs) {
- const [key, value] = pair.split("=");
+ const indexFirstEqual = pair.indexOf("=");
+
+ let key;
+ let value;
+
+ if (indexFirstEqual === -1) {
+ key = pair;
+ value = "";
+ } else {
+ key = pair.slice(0, indexFirstEqual);
+ value = pair.slice(indexFirstEqual + 1);
+ }
+
+ key = decodeURIComponent(key.replace(/\+/g, " "));
+ value = decodeURIComponent(value.replace(/\+/g, " "));
+
  queryParams[key] = value;
  }
 

Sprint-2/implement/querystring.test.js

@@ -3,46 +3,69 @@
 // 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({
+ const input = "equation=a=b-2";
+ const currentOutput = parseQueryString(input);
+ const targetOutput = {
  equation: "a=b-2",
- });
+ };
+
+ expect(currentOutput).toStrictEqual(targetOutput);
 });
 
 test("should ignore empty key-value pairs", () => {
- expect(parseQueryString("key1=value1&&key2=value2&")).toEqual({
+ const input = "key1=value1&&key2=value2&";
+ const currentOutput = parseQueryString(input);
+ const targetOutput = {
  key1: "value1",
  key2: "value2",
- });
+ };
+ expect(currentOutput).toEqual(targetOutput);
 });
-
 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({ "": "" });
+ expect(parseQueryString("=value")).toEqual({
+ "": "value",
+ });
+
+ expect(parseQueryString("key=")).toEqual({
+ key: "",
+ });
+
+ expect(parseQueryString("=")).toEqual({
+ "": "",
+ });
 });
 
+// test("should accept empty string as key or as value", () => {
+// const currentOutput = parseQueryString(input);
+// }
+// expect(currentOutput).toEqual(targetOutput);
+// 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({
- "full name": "John Doe",
- });
+ const input = "full+name=John+Doe";
+ const currentOutput = parseQueryString(input);
+ const expectedOutput = { "full name": "John Doe" };
+ expect(currentOutput).toEqual(expectedOutput);
 });
 
 // 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", () => {
+// const input = "key=value1&key=value2&key=value3&foo=bar";
+//const currentOutput = parseQueryString(input);
+//const expectedOutput = { key: ["value1", "value2", "value3"], foo: "bar" };
+// expect(currentOutput).toEqual(expectedOutput);
+// });

Sprint-2/implement/tally.js

@@ -1,3 +1,37 @@
-function tally() {}
+function tally(array) {
+ const charCount = {};
+
+ if (!Array.isArray(array)) {
+ throw new Error();
+ }
+
+ if (array.length === 0) {
+ return charCount;
+ }
+
+ for (const char of array) {
+ if (charCount[char]) {
+ charCount[char]++;
+ } else {
+ charCount[char] = 1;
+ }
+ }
+
+ return charCount;
+}
 
 module.exports = tally;
+
+/**
+ * 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 }
+ */

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("should return an empty oject when given an empty array", () => {
+ expect(tally([])).toEqual({});
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
 
-// Given an invalid input like a string
-// When passed to tally
-// Then it should throw an error
+test("should return counts for each unique item", () => {
+ expect(tally(["a", "b", "a", "b"])).toEqual({
+ a: 2,
+ b: 2,
+ });
+});
+// given an invalid input like a string
+//when passed to tally
+//then it should throw an error
+
+test("should throw an error when passed invalid input", () => {
+ expect(() => tally("")).toThrow(Error);
+});

Sprint-2/interpret/invert.js

@@ -10,20 +10,36 @@ function invert(obj) {
  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?
+//
+//[
+// ["a", 1],
+//["b", 2]
+//]
 
 // d) Explain why the current return value is different from the target output
+//invertedObj.key = value; means "create a property named key".
+//It does not mean "use the variable key as the property name."
+//invertedObj[value] = key; Square brackets allow the variable's value to become the property name.
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,18 @@
+const invert = require("./invert.js");
+
+test("should invert an object", () => {
+ expect(invert({ a: 1, b: 2 })).toEqual({
+ 1: "a",
+ 2: "b",
+ });
+});
+
+test("should invert an object with one property", () => {
+ expect(invert({ a: 1 })).toEqual({
+ 1: "a",
+ });
+});
+
+test("should return an empty object", () => {
+ expect(invert({})).toEqual({});
+});