📚 Cheatsheet

type ChaineOuNombre = string | number;
let maValeur: ChaineOuNombre;

function afficher(valeur: string | number) {
    if (typeof valeur === "string") {
        console.log(valeur.toUpperCase());
    }
}

interface A { a(): void }
interface B { b(): void }

let x: A & B;

let valeur: string | number;
valeur = "Bonjour";
valeur = 123;

type TypeNom<T> = T extends string ? "string" : "autre";

let direction: "gauche" | "droite" | "haut" | "bas";

type ReadonlyProps<T> = { readonly [P in keyof T]: T[P]; };

type TodoSansDescription = Omit<Todo, "description">;

interface Todo { title: string; description: string; }

function updateTodo(todo: Todo, fieldsToUpdate: Partial<Todo>) {
  return { ...todo, ...fieldsToUpdate };
}

type TodoPreview = Pick<Todo, "title">;

const todo: Readonly<Todo> = { title: "...", description: "..." };
// todo.title = "hello"; // Erreur