Object.isFrozen()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Die statische Methode Object.isFrozen()
bestimmt, ob ein Objekt
eingefroren ist.
Probieren Sie es aus
const object1 = {
property1: 42,
};
console.log(Object.isFrozen(object1));
// Expected output: false
Object.freeze(object1);
console.log(Object.isFrozen(object1));
// Expected output: true
Syntax
Object.isFrozen(obj)
Parameter
obj
-
Das Objekt, das überprüft werden soll.
Rückgabewert
Ein Boolean
, der angibt, ob das angegebene Objekt eingefroren ist oder nicht.
Beschreibung
Ein Objekt ist genau dann eingefroren, wenn es nicht erweiterbar ist, alle seine Eigenschaften nicht konfigurierbar sind und alle seine Dateneigenschaften (d. h. Eigenschaften, die keine Accessor-Eigenschaften mit Getter- oder Setter-Komponenten sind) nicht beschreibbar sind.
Beispiele
Verwendung von Object.isFrozen
// A new object is extensible, so it is not frozen.
Object.isFrozen({}); // false
// An empty object which is not extensible
// is vacuously frozen.
const vacuouslyFrozen = Object.preventExtensions({});
Object.isFrozen(vacuouslyFrozen); // true
// A new object with one property is also extensible,
// ergo not frozen.
const oneProp = { p: 42 };
Object.isFrozen(oneProp); // false
// Preventing extensions to the object still doesn't
// make it frozen, because the property is still
// configurable (and writable).
Object.preventExtensions(oneProp);
Object.isFrozen(oneProp); // false
// Deleting that property makes the object vacuously frozen.
delete oneProp.p;
Object.isFrozen(oneProp); // true
// A non-extensible object with a non-writable
// but still configurable property is not frozen.
const nonWritable = { e: "plep" };
Object.preventExtensions(nonWritable);
Object.defineProperty(nonWritable, "e", {
writable: false,
}); // make non-writable
Object.isFrozen(nonWritable); // false
// Changing that property to non-configurable
// then makes the object frozen.
Object.defineProperty(nonWritable, "e", {
configurable: false,
}); // make non-configurable
Object.isFrozen(nonWritable); // true
// A non-extensible object with a non-configurable
// but still writable property also isn't frozen.
const nonConfigurable = { release: "the kraken!" };
Object.preventExtensions(nonConfigurable);
Object.defineProperty(nonConfigurable, "release", {
configurable: false,
});
Object.isFrozen(nonConfigurable); // false
// Changing that property to non-writable
// then makes the object frozen.
Object.defineProperty(nonConfigurable, "release", {
writable: false,
});
Object.isFrozen(nonConfigurable); // true
// A non-extensible object with a configurable
// accessor property isn't frozen.
const accessor = {
get food() {
return "yum";
},
};
Object.preventExtensions(accessor);
Object.isFrozen(accessor); // false
// When we make that property non-configurable it becomes frozen.
Object.defineProperty(accessor, "food", {
configurable: false,
});
Object.isFrozen(accessor); // true
// But the easiest way for an object to be frozen
// is if Object.freeze has been called on it.
const frozen = { 1: 81 };
Object.isFrozen(frozen); // false
Object.freeze(frozen);
Object.isFrozen(frozen); // true
// By definition, a frozen object is non-extensible.
Object.isExtensible(frozen); // false
// Also by definition, a frozen object is sealed.
Object.isSealed(frozen); // true
Nicht-Objekt-Argument
In ES5 führt die Übergabe eines Arguments, das kein Objekt ist (ein primitiver Wert), zu einem TypeError
. In ES2015 gibt diese Methode jedoch true
ohne Fehler zurück, wenn ein nicht-objektbezogenes Argument übergeben wird, da primitive Werte definitionsgemäß unveränderlich sind.
Object.isFrozen(1);
// TypeError: 1 is not an object (ES5 code)
Object.isFrozen(1);
// true (ES2015 code)
Spezifikationen
Specification |
---|
ECMAScript® 2025 Language Specification # sec-object.isfrozen |
Browser-Kompatibilität
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
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isFrozen |
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