The Object.getOwnPropertySymbols() static method returns an array of all symbol properties found directly upon a given object.
const object = {};
const a = Symbol("a");
const b = Symbol.for("b");
object[a] = "localSymbol";
object[b] = "globalSymbol";
const objectSymbols = Object.getOwnPropertySymbols(object);
console.log(objectSymbols.length);
// Expected output: 2Object.getOwnPropertySymbols(obj)objThe object whose symbol properties are to be returned.
An array of all symbol properties found directly upon the given object.
Similar to Object.getOwnPropertyNames(), you can get all symbol properties of a given object as an array of symbols. Note that Object.getOwnPropertyNames() itself does not contain the symbol properties of an object and only the string properties.
As all objects have no own symbol properties initially, Object.getOwnPropertySymbols() returns an empty array unless you have set symbol properties on your object.
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)