Addition et affectation (+=)

let a = 2;
let b = "bonjour";

console.log((a += 3)); // Addition
// Rsultat attendu : 5

console.log((b += " le monde")); // Concatnation
// Rsultat attendu : "bonjour le monde"

x += y

let truc = 5;
truc += 2; // 7

let machin = true;
machin += 1; // 2
machin += false; // 2

let x = 1n;
x += 2n; // 3n

x += 1; // TypeError: Cannot mix BigInt and other types, use explicit conversions

let toto = "toto";
toto += false; // "totofalse"
toto += "truc"; // "totofalsetruc"

let truc = 5;
truc += "toto"; // "5toto"