Learn ECMAScript - Second Edition

The Object.getOwnPropertySymbols() method

The Object.getOwnPropertyNames() method cannot retrieve the symbol properties. Therefore, ES6 introduced Object.getOwnPropertySymbols() to retrieve an array of symbol properties of an object. Here is an example to demonstrate this:

let obj = {a: 12};let s1 = Symbol("mySymbol");let s2 = Symbol("mySymbol");Object.defineProperty(obj, s1, {enumerable: false});obj[s2] = "";console.log(Object.getOwnPropertySymbols(obj));

The output is as follows:

Symbol(mySymbol),Symbol(mySymbol)

From the previous example, you can see that the Object.getOwnPropertySymbols() method can also retrieve the non-enumerable symbol properties.

The in operator can find the symbol properties in an object, whereas the for…in loop ...