Name	Name	Last commit message	Last commit date
parent directory ..
task_1	task_1
task_3	task_3
task_7	task_7
README.md	README.md

📖 0x04-TypeScript.

📃 Topics Covered

ES6 Data Structures;
1. Array and Typed Array Data Structure.
2. Map and WeakMap Data Structure.
3. Set Data Structure.

💻 Tasks.

0. Creating an interface for a student

📃 Task requirements.

🔧 Task setup.

# Create task file and set execute permission.
mkdir -p task_0/js/
touch ./task_0/js/main.ts
chmod +x ./task_0/js/main.ts

# Create a new node project
touch task_0/package.json

echo '{
  "name": "typescript_dependencies",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start-dev": "webpack-dev-server --open",
    "build": "webpack",
    "test": "jest"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/plugin-proposal-export-default-from": "^7.5.2",
    "@babel/preset-typescript": "^7.7.2",
    "@types/jest": "^24.0.23",
    "@typescript-eslint/eslint-plugin": "^2.4.0",
    "@typescript-eslint/parser": "^2.4.0",
    "clean-webpack-plugin": "^3.0.0",
    "fork-ts-checker-webpack-plugin": "^1.5.1",
    "html-webpack-plugin": "^3.2.0",
    "jest": "^24.9.0",
    "source-map": "^0.7.3",
    "ts-jest": "^24.1.0",
    "ts-loader": "^6.2.0",
    "typescript": "^3.6.4",
    "webpack": "^4.41.2",
    "webpack-cli": "^3.3.9",
    "webpack-dev-server": "^3.8.2"
  }
}' >> task_0/package.json

# Configure eslint.
touch task_0/.eslintrc.js

echo 'module.exports =  {
  parser:  '@typescript-eslint/parser',
  extends:  [
    'plugin:@typescript-eslint/recommended',  // Uses the recommended rules from @typescript-eslint/eslint-plugin
  ],
  parserOptions:  {
    ecmaVersion:  2018,
    sourceType:  'module',
  },
  rules:  {
  },
};' >> task_0/.eslintrc.js

# Configure typescript.
touch task_0/tsconfig.json

echo '{
  "compilerOptions": {
    "outDir": "./dist/",
    "sourceMap": true,
    "noImplicitAny": true,
    "module": "es6",
    "target": "es5",
    "allowJs": true,
    "moduleResolution": "node"
  }
}' >> task_0/tsconfig.json

# Configure webpack.
touch task_0/webpack.config.js

echo 'const path = require("path");
const HtmlWebpackPlugin = require('html-webpack-plugin');
const { CleanWebpackPlugin } = require('clean-webpack-plugin');
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
  entry: "./js/main.ts",
  devtool: "inline-source-map",
  module: {
    rules: [
      {
        test: /\.tsx?$/,
        loader: 'ts-loader',
        options: {
          transpileOnly: true
        }
      }
    ]
  },
  resolve: {
    extensions: [".tsx", ".ts", ".js"]
  },
  devServer: {
    contentBase: "./dist"
  },
  plugins: [
    new ForkTsCheckerWebpackPlugin(),
    new CleanWebpackPlugin(),
    new HtmlWebpackPlugin({
      title: "Development"
    })
  ],
  output: {
    filename: "bundle.js",
    path: path.resolve(__dirname, "dist")
  }
};
' >> task_0/webpack.config.js

# Change directory to task folder.
cd ./task_0

# Install node packages.
npm i

# Run project.
npm run start-dev

✔️ Solution

👉 task_0

1. Let's build a Teacher interface

📃 Task requirements.

Create a directory task_1 and copy these configuration files into this folder: package.json, tsconfig.json, webpack.config.js

firstName(string) and lastName(string). These two attributes should only be modifiable when a Teacher is first initialized
fullTimeEmployee(boolean) this attribute should always be defined
yearsOfExperience(number) this attribute is optional
location(string) this attribute should always be defined
Add the possibility to add any attribute to the Object like contract(boolean) without specifying the name of the attribute

Example:

const teacher3: Teacher = {
  firstName: 'John',
  fullTimeEmployee: false,
  lastName: 'Doe',
  location: 'London',
  contract: false,
};

console.log(teacher3);

// should print
// Object
// contract: false
// firstName: "John"
// fullTimeEmployee: false
// lastName: "Doe"
// location: "London"

🔧 Task setup.

# Create task files and set execute permission.
cp -r task_0 task_1

✔️ Solution

👉 task_1

2. Extending the Teacher class

📃 Task requirements.

Write an interface named Directors that extends Teacher. It requires an attribute named numberOfReports(number)

Example:

const director1: Directors = {
  firstName: 'John',
  lastName: 'Doe',
  location: 'London',
  fullTimeEmployee: true,
  numberOfReports: 17,
};
console.log(director1);

// should print
// Object
// firstName: "John"
// fullTimeEmployee: true
// lastName: "Doe"
// location: "London"
// numberOfReports: 17

🔧 Task setup.

# Create task file and set execute permission.
cp -r task_1 task_2

# Run project
npm run start-dev

✔️ Solution

👉 task_2

[5. Advanced types Part 1 (task_5)

📃 Task requirements.

Create the DirectorInterface interface with the 3 expected methods:

workFromHome() returning a string
getCoffeeBreak() returning a string
workDirectorTasks() returning a string

Create the TeacherInterface interface with the 3 expected methods:

workFromHome() returning a string
getCoffeeBreak() returning a string
workTeacherTasks() returning a string

Create a class Director that will implement DirectorInterface

workFromHome should return the string Working from home
getToWork should return the string Getting a coffee break
workDirectorTasks should return the string Getting to director tasks

Create a class Teacher that will implement TeacherInterface

workFromHome should return the string Cannot work from home
getCoffeeBreak should return the string Cannot have a break
workTeacherTasks should return the string Getting to work

Create a function createEmployee with the following requirements:

It can return either a Director or a Teacher instance
It accepts 1 arguments: salary(either number or string)
if salary is a number and less than 500 - It should return a new Teacher. Otherwise it should return a Director Expected result:

console.log(createEmployee(200));
Teacher
console.log(createEmployee(1000));
Director
console.log(createEmployee('$500'));
Director

🔧 Task setup.

# Create task file and set execute permission.
cp -r task_4 task_5

# Run project
cd task_5
npm run start-dev

✔️ Solution

👉 task_5

6. Creating functions specific to employees

Task requirements

Write a function isDirector:

it accepts employee as an argument
it will be used as a type predicate and if the employee is a director

Write a function executeWork:

it accepts employee as an argument
if the employee is a Director, it will call workDirectorTasks
if the employee is a Teacher, it will call workTeacherTasks

Expected result:

executeWork(createEmployee(200));
Getting to work
executeWork(createEmployee(1000));
Getting to director tasks

Task setup

# Create task file and set execute permission.
cp -r task_5 task_6

# Run project
cd task_6
npm run start-dev

✔️ Solution

👉 task_6

8. Ambient Namespaces

Task requirements

Create a directory called task_3 and copy these configuration files into it: package.json, webpack.config.js, tsconfig.json.

The first part of will require that you build an interface and a type. Inside a file named interface.ts:

Create a type RowID and set it equal to number
Create an interface RowElement that contains these 3 fields:
- firstName: string
- lastName: string
- age?: number

You are building the next part of the application architecture. The goal is to save the entities to a database. Because of time constraints, you can’t write a connector to the database, and you decided to download a library called crud.js. Copy this file into the task_3/js directory.

Here it is

export function insertRow(row) {
  console.log('Insert row', row);
  return Math.floor(Math.random() * Math.floor(1000));
}

export function deleteRow(rowId) {
  console.log('Delete row id', rowId);
  return;
}

export function updateRow(rowId, row) {
  console.log(`Update row ${rowId}`, row);

  return rowId;
}

Write an ambient file within task_3/js, named crud.d.ts containing the type declarations for each crud function. At the top of the file import RowID and RowElement from interface.ts.

In main.ts

At the top of the file create a triple slash directive that includes all the dependencies from crud.d.ts
Import the rowID type and rowElement from interface.ts
Import everything from crud.js as CRUD

Create an object called row with the type RowElement with the fields set to these values:

firstName: Guillaume
lastName: Salva

Create a const variable named newRowID with the type RowID and assign the value the insertRow command.

Next, create a const variable named updatedRow with the type RowElement and update row with an age field set to 23

Finally, call the updateRow and deleteRow commands.

Expected result:

const obj = {firstName: "Guillaume", lastName: "Salva"};
CRUD.insertRow(obj)
// Insert row {firstName: "Guillaume", lastName: "Salva"}

const updatedRow: RowElement = { firstName: "Guillaume", lastName: "Salva", age: 23 };
CRUD.updateRow(newRowID, updatedRow);
// Update row 125 {firstName: "Guillaume", lastName: "Salva", age: 23}

CRUD.deleteRow(125);
// Delete row id 125

Requirements:

When running npm run build, no TypeScript error should be displayed.
Every variable should use TypeScript when possible.
The main file and the ambient file should both import the types defined in the interface file.
You can easily test your ambient file by looking at the intellisense of your IDE when using the 3rd party functions.

Task setup

# Create task file and set execute permission.
cp -r task_0 task_3

touch task_3/js/interface.ts
chmod +x task_3/js/interface.ts

touch task_3/js/crud.js
chmod +x task_3/crud.js

touch task_3/js/crud.d.ts
chmod +x task_3/crud.d.ts

# Run project
cd task_8
npm run start-dev

✔️ Solution

👉 task_8

9. Namespace & Declaration merging

Task requirements

Create a new directory task_4 and copy the above tsconfig.json and put this package.json in there

{
  "name": "task_4",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "webpack",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@typescript-eslint/eslint-plugin": "^2.4.0",
    "@typescript-eslint/parser": "^2.4.0",
    "clean-webpack-plugin": "^3.0.0",
    "fork-ts-checker-webpack-plugin": "^1.5.1",
    "html-webpack-plugin": "^3.2.0",
    "ts-loader": "^6.2.0",
    "typescript": "^3.6.4",
    "webpack": "^4.41.2",
    "webpack-cli": "^3.3.9",
    "webpack-dev-server": "^3.8.2"
  }
}

In task_4/js/subjects:

Create a file Teacher.ts and write a Teacher interface in a namespace named Subjects.
- the interface requires firstName and lastName as string
Create a file Subject.ts and write a Subject class in the same namespace named Subjects.
- the class has one attribute teacher that implements the Teacher interface
- the class has one setter method setTeacher that accepts a teacher in argument (and as setter, set the instance attribute teacher with it)
Create a file Cpp.ts and make the following modifications in the same namespace.
- Using declaration merging, add a new optional attribute experienceTeachingC (number) to the Teacher interface
- Create a class Cpp extending from Subject Write a method named getRequirements that will return a string Here is the list of requirements for Cpp
- Write a method named getAvailableTeacher that will return a string Available Teacher:
- If the teacher doesn’t have any experience in teaching C, then the method should return a string No available teacher
Create a file React.ts and write a React Class in the same namespace.
- Add a new attribute experienceTeachingReact? (number) to the Teacher interface
- In the class, write a method named getRequirements that will return a string Here is the list of requirements for React
- Write a method named getAvailableTeacher that will return a string Available Teacher:
- If the teacher doesn’t have any experience in teaching React, then the method should return a string No available teacher
Create a file Java.ts and write a Java Class in the same namespace.
- Add a new attribute experienceTeachingJava? (number) to the Teacher interface
- In the class, write a method named getRequirements that will return a string Here is the list of requirements for Java
- Write a method named getAvailableTeacher that will return a string Available Teacher:
- If the teacher doesn’t have any experience in teaching Java, then the method should return a string No available teacher

Task setup

# Create task file and set execute permission.
cp -r task_3 task_4
mkdir -p task_4/js/subjects
touch task_4/js/subjects/Cpp.ts task_4/js/subjects/Java.ts task_4/js/subjects/React.ts task_4/js/subjects/Subject.ts task_4/js/subjects/Teacher.ts

# Run project
cd task_4
npm run build

✔️ Solution

👉 task_4

9. Namespace & Declaration merging

Task requirements

create and export a constant cpp for Cpp Subjects
create and export a constant java for Java Subjects
create and export a constant react for React Subjects
create and export one Teacher object cTeacher with experienceTeachingC = 10
for Cpp subject, log to the console C++, set cTeacher as the teacher, call the two methods getRequirements and getAvailableTeacher and print the strings they return
for Java subject, log to the console Java, set cTeacher as the teacher, call the two methods getRequirements and getAvailableTeacher, and print the strings they return
for React subject, log to the console React, set cTeacher as the teacher, call the two methods getRequirements and getAvailableTeacher, and print the strings they return

Task setup

# Run project
cd task_4
npm run build

✔️ Solution

👉 task_4

11. Brand convention & Nominal typing

Task requirements

Create a directory task_5 and copy these configuration files into the root of task_5: package.json, tsconfig.json, webpack.config.js

Create two interfaces MajorCredits and MinorCredits in task_5/js/main.ts:

Each interface defines a number named credits
Add a brand property to each interface in order to uniquely identify each of them

Create two functions named sumMajorCredits and sumMinorCredits in task_5/js/main.ts:

Each function takes two arguments subject1 and subject2
sumMajorCredits returns MajorCredits value and sumMinorCredits returns MinorCredits value
Each function sums the credits of the two subjects

Task setup

# Run project
cd task_5
npm run start-dev

✔️ Solution

👉 task_5

📚 References

👨 Author and Credits.

This project was done by SE. Moses Mwangi. Feel free to get intouch with me;

📱 WhatsApp +254115227963

📧 Email moses.soft.eng@gmail.com

👍 A lot of thanks to ALX-Africa Software Engineering program for the project and learning resources.

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📖 0x04-TypeScript.

📃 Topics Covered

💻 Tasks.

📃 Task requirements.

🔧 Task setup.

✔️ Solution

📃 Task requirements.

🔧 Task setup.

✔️ Solution

📃 Task requirements.

🔧 Task setup.

✔️ Solution

📃 Task requirements.

🔧 Task setup.

✔️ Solution

Task requirements

Task setup

✔️ Solution

[5. Advanced types Part 1 (task_5)

📃 Task requirements.

🔧 Task setup.

✔️ Solution

Task requirements

Task setup

✔️ Solution

Task requirements

Task setup

✔️ Solution

Task requirements

Task setup

✔️ Solution

Task requirements

Task setup

✔️ Solution

Task requirements

Task setup

✔️ Solution

Task requirements

Task setup

✔️ Solution

📚 References

👨 Author and Credits.