Object.isSealed() - JavaScript | MDN

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In ES5, if the argument to this method is not an object (a primitive), then it will cause a TypeError. In ES2015, it will return true without any errors if a non-object argument is passed, since primitives are, by defini

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This page was last modified on Jul 20, 2025 by MDN contributors.

defineProperties()

getOwnPropertyDescriptor()

getOwnPropertyDescriptors()

getOwnPropertyNames()

getOwnPropertySymbols()

__defineGetter__()

__defineSetter__()

__lookupGetter__()

__lookupSetter__()

propertyIsEnumerable()

[Symbol.hasInstance]()

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