Symbol() コンストラクター

const symbol1 = Symbol();
const symbol2 = Symbol(42);
const symbol3 = Symbol("foo");
console.log(typeof symbol1);
// Expected output: "symbol"
console.log(symbol2 === 42);
// Expected output: false
console.log(symbol3.toString());
// Expected output: "Symbol(foo)"
console.log(Symbol("foo") === Symbol("foo"));
// Expected output: false

Symbol()
Symbol(description)

const sym1 = Symbol();
const sym2 = Symbol("foo");
const sym3 = Symbol("foo");

Symbol("foo") === Symbol("foo"); // false

const sym = new Symbol(); // TypeError

const sym = Symbol("foo");
const symObj = Object(sym);
typeof sym; // "symbol"
typeof symObj; // "object"