The Reflect.ownKeys()
static method returns an array of the target
object's own property keys.
The Reflect.ownKeys()
static method returns an array of the target
object's own property keys.
Reflect.ownKeys(target)
target
The target object from which to get the own keys.
An Array
of the target
object's own property keys, including strings and symbols. For most objects, the array will be in the order of:
TypeError
Thrown if target
is not an object.
Reflect.ownKeys()
provides the reflective semantic of retrieving all property keys of an object. It is the only way to get all own properties – enumerable and not enumerable, strings and symbols — in one call, without extra filtering logic. For example, Object.getOwnPropertyNames()
takes the return value of Reflect.ownKeys()
and filters to only string values, while Object.getOwnPropertySymbols()
filters to only symbol values. Because normal objects implement [[OwnPropertyKeys]]
to return all string keys before symbol keys, Reflect.ownKeys(target)
is usually equivalent to Object.getOwnPropertyNames(target).concat(Object.getOwnPropertySymbols(target))
. However, if the object has a custom [[OwnPropertyKeys]]
method (such as through a proxy's ownKeys
handler), the order of the keys may be different.
Reflect.ownKeys()
invokes the [[OwnPropertyKeys]]
object internal method of target
.
Reflect.ownKeys({ z: 3, y: 2, x: 1 }); // [ "z", "y", "x" ] Reflect.ownKeys([]); // ["length"] const sym = Symbol.for("comet"); const sym2 = Symbol.for("meteor"); const obj = { [sym]: 0, str: 0, 773: 0, 0: 0, [sym2]: 0, "-1": 0, 8: 0, "second str": 0, }; Reflect.ownKeys(obj); // [ "0", "8", "773", "str", "-1", "second str", Symbol(comet), Symbol(meteor) ] // Indexes in numeric order, // strings in insertion order, // symbols in insertion order
Specification |
---|
ECMAScript Language Specification # sec-reflect.ownkeys |
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | Deno | Node.js | ||
ownKeys |
49 | 12 | 42 | 36 | 10 | 49 | 42 | 36 | 10 | 5.0 | 49 | 1.0 | 6.0.0 |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Reflect/ownKeys