How to Get an Array of JavaScript Object's Own Keys?

You can get an array of an object's own keys in JavaScript in the following ways:

• Using Object.keys() — returns only own enumerable keys (except Symbol);
• Using Object.getOwnPropertyNames() — returns all own keys (except Symbol);
• Using Object.getOwnPropertySymbols() — returns all own Symbol keys.

Using Object.keys()

The Object.keys() method returns an array of object's own enumerable property names (excluding Symbol properties):

// ES5+
const sym1 = Symbol('a');
const sym2 = Symbol('b');

const obj = Object.create({}, {
    foo: { value: 'bar', enumerable: true },
    baz: { value: 'qux', enumerable: false },
    [sym1]: { value: 'quux', enumerable: true },
    [sym2]: { value: 'quuz', enumerable: false },
});

const keys = Object.keys(obj);

console.log(keys); // [ 'foo' ]

Using Object.getOwnPropertyNames()

The Object.getOwnPropertyNames() method returns an array of all object's own string property names (including non-enumerable properties, and excluding Symbol properties):

// ES5+
const sym1 = Symbol('a');
const sym2 = Symbol('b');

const obj = Object.create({}, {
    foo: { value: 'bar', enumerable: true },
    baz: { value: 'qux', enumerable: false },
    [sym1]: { value: 'quux', enumerable: true },
    [sym2]: { value: 'quuz', enumerable: false },
});

const keys = Object.getOwnPropertyNames(obj);

console.log(keys); // [ 'foo', 'baz' ]

Using Object.getOwnPropertySymbols()

The Object.getOwnPropertySymbols() method returns an array of object's own Symbol properties (excluding all other string properties):

// ES6+
const sym1 = Symbol('a');
const sym2 = Symbol('b');

const obj = Object.create({}, {
    foo: { value: 'bar', enumerable: true },
    baz: { value: 'qux', enumerable: false },
    [sym1]: { value: 'quux', enumerable: true },
    [sym2]: { value: 'quuz', enumerable: false },
});

const keys = Object.getOwnPropertySymbols(obj);

console.log(keys); // [Symbol(a), Symbol(b)]

Please note that all objects have no own Symbol properties initially, therefore, Object.getOwnPropertySymbols() returns an empty array (unless you explicitly set Symbol properties on an object).