Object.isSealed() static method determines if an object is sealed.

syntax ↴

Object.isSealed(obj) ↴

obj The object which should be checked.

Object.isSealed() returns true if an object is sealed.

Object.isSealed() returns false if an object is not sealed.

An object is sealed if all of the below-mentioned conditions hold true ↴

if it is not extensible,

if all of its properties are non-configurable,

if it is not removable, (but not necessarily non-writable).

Object.seal() method seals an object so that new properties cannot be added, existing properties cannot be removed, their enumerability and configurability cannot be changed, and its prototype cannot be re-assigned. Values of existing properties can still be changed as long as they are writable.

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