It's just JavaScript

Here's some TypeScript code:
const array = [1, 2, 3, 4, 5]
​
function squareNumber(num) {
    return num * num
}
​
const squared = array.map(squareNumber)
​
squared // [1, 4, 9, 16, 25]
array // [1, 2, 3, 4, 5]
​
const doubled = array.map(num => num * 2); // [2, 4, 6, 8, 10]
​
const books = [
    {
        name: "JavaScript: The Definitive Guide",
        description: `Since 1996, JavaScript: The Definitive Guide...`,
        price: 28.89
    },
    {
        name: "Eloquent JavaScript",
        description: `JavaScript lies at the heart...`,
        price: 21.22
    },
    {
        name: "JavaScript: The Good Parts",
        description: `Most programming languages...`,
        price: 16.59
    }
];
​
const getTitle = book => book.name;
​
const titles = books.map(getTitle);
​
const titlesOfExpensiveBooks = books
    .filter(book => book.pirce > 20)
    .map(getTitle);
What's the point then? Let's take a look.
Benefits of TypeScript
type safety
your editor gets smarter
no need for as many unit tests as you need now
almost no entry cost if you already know JS 
most (?) of the latest JS features
By the way
During this workshop we'll be using the latest version of TypeScript (3.6.3) that has been installed with create-react-app on project creation.
If you haven't created a project yet, now's the last chance, here's what to do:
npx create-react-app react-ts-devmeeting --typescript
cd react-ts-devmeeting && npm start
Resources
​Typescript playground​

Typescript

Basic types

Last modified 2yr ago

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Benefits of TypeScript

By the way

Resources