A la découverte de TypeScript

À la découverte de
Denis Voituron

Agenda
• Installation
• JavaScript Strongly Typed
• Object Oriented Programming
• Find your Data with LINQ
• Asynchronous Programming
• Bests Practices
• Advantages and Disadvantages
• Conclusion

EcmaScript
ES8
(ES2017)
ES7
(ES2016)
ES6
(ES2015)
ES5
ES3

JavaScript
Problèmes du langage
• Langage interprété
• Absence de modules
• Typage faible
• Conversions automatiques
• Portée (this)
• Manque de types statiques

Programming language
Superset of JavaScript
Transpiled into JavaScript
Open Source
Developped by Microsoft, supported by Google
lang.org

«Microsoft's TypeScript may be the best of the
many Javascript front ends. It seems to generate
the most attractive code.»
https://insights.stackoverflow.com/survey/2018

Installation
• Visual Studio Code : https://code.visualstudio.com
• NodeJS et NPM : https://nodejs.org
• TypeScript :
• http-Server (Node) :
npm install TypeScript -g
npm install http-server -g

Reload Window
& Open TS file
Specifies the folder path containing
the tsserver and lib*.d.ts files to use.

Sample
function startGame() {
var myMessage = document.getElementById("message");
myMessage.innerText = "Hello world";
}
document.getElementById("btnStart").addEventListener("click", startGame);
HelloWorld.ts
<html>
<body>
<div id="message"></div>
<button id="btnStart">Start</button>
<script src="HelloWorld.js"></script>
</body>
</html>
Index.html
tsc HelloWorld.ts

tsconfig.json
• Target ECMAScript 5
• SourceMap Debugging in Chrome
• Strict Object is possibly 'null’
• Watch Run ‘tsc’ and update files
• …
{
"compilerOptions": {
"target": "es5",
"noImplicitAny": true,
"sourceMap": true,
"watch": true,
"strict": true,
"removeComments": true,
"outDir": "./dist"
},
"include": [
"./**/*.ts"
],
"exclude": [
"node_modules"
]
}
tsconfig.json
tsc --init
https://html5test.com

Basic Types
Boolean - Number - String - Array - Enum
var name: string = "Denis"
var age: number = 21
var birthdate: Date;
var name = "Denis";
var age = 21;
var birthdate;
birthdate.

Declarations with let and const
console.log(someString);
var someString = "hello World";
let someString = "hello World";
console.log(someString);
const someString = "hello World";
someString = "a new World";

Type Annotations and Type Inference
let x: string = "Hello World";
x = 42;
let x = "Hello World";
x = 42;
let name: string = "Voituron";
let message = `My name is ${name}`;

Union Types, Null, Undefined
{
"strictNullChecks": true,
...
let x: string;
x = null;
x = undefined;
let y: string | null;
y = null;
y = undefined;
let z: string | number | null;
z = null;
z = "Hello";
z = 123;

Type Assertions
let value: any = 5;
let fixedString: string = (<number>value).toFixed(4);
console.log(fixedString) // 5.0000
let value: any = 5;
let fixedString: string = (value as number).toFixed(4);
console.log(fixedString) // 5.0000

Demo
+ showSolution(HTMLElement): void
+ play(): void
- checkSolution(): Boolean
+ static solution: RowOfBalls
+ static rows: RowOfBalls[ ]
+ color: Colors
+ isClickable: boolean
+ render(): HTMLImageElement
+ render(): HTMLElement
+ Red
+ Green
+ Yellow
+ Blue
+ White
+ balls: Ball[ ]
+ isClickable: boolean
+ goodBalls: number
+ render(): HTMLImageElement

Method
function getSurface(width: number): number {
return width * width;
}
function getSurface(width): number {
}
[ts] Parameter 'width' implicitly
has an 'any' type.

Overloaded Methods
// Signatures
function getSurface(width: number): number;
function getSurface(width: number, height: number): number;
// Main method
function getSurface(width: number, height?: number): number {
if (height == null)
else
return width * height;
}

Default value
function getSurface(width: number, height: number = width): number {
return width * height;
}
getSurface(10); // 100
getSurface(10, 5); // 50

Anonymous methods
let square = (x: number) => x * x;
square(2); // 4
let add = (a: number, b: number) => a + b;
add(2, 3); // 5
let add = (a: number, b: number) => { return a + b };

Static Members
class WebDeveloper extends Developer {
static jobDescription = "Build cool things";
static logFavoriteProtocol() {
console.log("HTTPS, of course");
}
writeTypeScript(): void {
console.log(WebDeveloper.jobDescription);
}
}

Generic
"lib": [ "es6" ]
let list = new Set<number>([0, 1]);
list.add(2)
let dico = new Map<string, number>([["k1", 0], ["k2", 1]]);
dico.set("k1", 2);
let array = new Array<string>();
array.push("Hello");

Generic
class Queue {
private data = [];
push = (item) => this.data.push(item);
pop = () => this.data.shift();
}
const queue = new Queue();
queue.push(0);
queue.push("1"); // RUNTIME ERROR
"lib": [ "es6" ]

Generic
class QueueNumber {
private data = [];
push = (item: number) => this.data.push(item);
pop = (): number => this.data.shift();
}
const queue = new QueueNumber();
queue.push(0);
queue.push("1"); // COMPILATION ERROR
class Queue<T> {
private data = [];
push = (item: T) => this.data.push(item);
pop = (): T => this.data.shift();
}
const queue = new Queue<number>();
queue.push(0);
queue.push("1"); // COMPILATION ERROR

Interfaces vs Classes
Classes
Define a new type
Properties (with implementation)
Methods (with implémentation)
Can be instantiated
Interfaces
Define a new type
Properties (signatures)
Methods (signatures)
Cannot be instantiated

Interfaces
interface Employee {
name: string;
title: string;
}
interface Manager extends Employee {
department: string;
numOfEmployees: number;
scheduleMeeting: (topic: string) => void;
}
let developer: Employee = {
name: "Voituron",
title: "Developer"
}

Classes
Module Oniryx.Myproject {
class Developer {
department: string;
private _title : string;
public get title() : string {
return this._title;
}
public set title(value : string) {
this._title = value;
}
public requirements(value: string): void {
console.log(value);
}

Extending a class, implementing an interface
favoriteEditor: string;
writeTypeScript(): void {
// Write code
}
}
/// <reference path="Employee.ts" />
class Engineer implements Employee {
name: string;
title: string;
}

Constructors
class Developer {
public department: string;
public title: string;
constructor() {
console.log("Creating a new developer");
}
}

Constructors
class Developer {
public department: string;
public title: string;
constructor() {
}
}
readonly favoriteEditor: string;
constructor(editor: string) {
super();
this.favoriteEditor = editor;
}
}

Constructors
class Developer {
constructor(public department: string, public title: string) {
}
}
readonly favoriteEditor: string;
constructor(editor: string) {
super();
this.favoriteEditor = editor;
}
}

Extension methods
// global.d.ts
interface Date {
isInFuture(): boolean;
}
Date.prototype.isInFuture = function(): boolean {
return (this != null && this.valueOf() > Date.now());
}

Modules
• CommonJS
• SystemJS
{
"target": "es5",
"module": "commonjs",
"moduleResolution": "node",
"traceResolution": true,
default

Exporting a declaration
export interface Person { }
class Manager { } // Not accessible outside the module
import { Person } from "./Person";
let manager: Person

Exporting a declaration
export interface Person { }
class Manager { } // Not accessible outside the module
import * as People from "./Person";
let manager: People.Person

src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.21.0/system.js"></script>
<script>
SystemJS.config({
map: {
jquery: 'https://code.jquery.com/jquery.js',
linqts: '/node_modules/linqts/dist/linqts.js'
},
packages: {
}
});
</script>
Linq for TypeScript
• SystemJS Loader
npm install linqts
https://github.com/kutyel/linq.ts

Linq for TypeScript https://github.com/kutyel/linq.ts
import { List } from "linqts"
const arr = new List<number>([1, 2, 3, 4, 5])
.Where(x => x > 3)
.Select(y => y * 2)
.ToArray(); // > [8, 10]

npm install linqts
import { List } from "linqts"
let people = new List([
{ Name: "Alice", Age: 25 },
{ Name: "Bob", Age: 50 },
{ Name: "Kathy", Age: 15 }
]);
let alice = people.FirstOrDefault(i => i.Age > 18).Name;

Project Select
Filter Where, Distinct
Test Any, All
Join Join
Group GroupBy, Group Join
Aggregate Count, Min, Max, Sum, Avg
Partition Skip, SkipWhile, Take, TakeWhile
Set Union, Intersect, Except
Order OrderBy, OrderByDescending

Async / Await
• Promiseclass HelloWorld {
public delay(ms: number): Promise<void> {
return new Promise<void>((resolve) => {
setTimeout(resolve, ms);
});
}
}
A Promise is an object representing the eventual
completion or failure of an asynchronous operation.
"target": "es5",
"lib": [
"es6", "dom"
]
},

Async / Await
• Promise
• async / await
class HelloWorld {
public delay(ms: number): Promise<void> {
return new Promise<void>((resolve) => {
setTimeout(resolve, ms);
});
}
public async asyncAwait(): Promise<void> {
document.write("Knock, knock! <br/>");
await this.delay(3000); // 3 seconds
document.write("Who's there? <br/>");
}
}
new HelloWorld().asyncAwait(); // Start

Compile and Build tsconfig.json
{
"version": "2.0.0",
"tasks": [
{
"type": "typescript",
"tsconfig": "tsconfig.json",
"problemMatcher": [ "$tsc“ ],
"group": {
"kind": "build",
"isDefault": true
}
}
]
}
.vscodetasks.json
{
"target": "es5",
"module": "commonjs",
"moduleResolution": "node",
"traceResolution": true,
"noImplicitAny": true,
"sourceMap": true,
"watch": true,
"strict": true,
"strictNullChecks": true,
"removeComments": true,
"outDir": "./dist",
"lib": [ "es6", "dom" ]
},
"include": [
"./**/*.ts"
],
"exclude": [
"node_modules"
]
}

src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.21.0/system.js">
</script>
<script>
SystemJS.config({
map: {
jquery: 'https://code.jquery.com/jquery.js',
linqts: '/node_modules/linqts/dist/linqts.js'
},
packages: {
}
});
</script>
Module Loader

Do's and Don'ts
• General Types
• Callback Types
• Optional Parameters in Callbacks
• Overloads and Callbacks
• Function Overloads
https://www.typescriptlang.org/docs/handbook/declaration-files/do-s-and-don-ts.html

Slides: https://slideshare.net/dvoituron
Code: https://github.com/dvoituron /TypeScriptMasterMind (branches)

A la découverte de TypeScript

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