Object.isFrozen()
Determines whether an object is frozen.
Syntax
Object.isFrozen(obj)Parameters
| Name | Type | Required | Description |
|---|---|---|---|
obj | object | Yes | The object to test. |
Returns
boolean — true if the object is frozen; otherwise false.
Examples
const o = Object.freeze({ a: 1 });
console.log(Object.isFrozen(o));
Output
true
console.log(Object.isFrozen({}));
Output
false
Notes
Primitives are considered frozen and return true (since ES2015). An object is
frozen when it is non-extensible and all its own properties are non-configurable
and non-writable.
Browser & runtime support
| Environment | Since version |
|---|---|
| chrome | 6 |
| firefox | 4 |
| safari | 5.1 |
| edge | 12 |
| node | 0.10 |