Object.getOwnPropertySymbols(obj) 静态方法返回一个包含给定对象所有自有 Symbol 属性的数组。
const obj = {};
const a = Symbol("a");
const b = Symbol.for("b");
obj[a] = "localSymbol";
obj[b] = "globalSymbol";
const objectSymbols = Object.getOwnPropertySymbols(obj);
console.log(objectSymbols.length); // 2
console.log(objectSymbols); // [Symbol(a), Symbol(b)]
console.log(objectSymbols[0]); // Symbol(a)
