WeakRef - JavaScript | MDN

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non-registered symbols

Because non-registered symbols are also garbage collectable, they can also be used as the target of a WeakRef object. However, the use case of this is limited.

FinalizationRegistry

WeakRef.prototype.constructor

The constructor function that created the instance object. For WeakRef instances, the initial value is the WeakRef constructor.

[Symbol.toStringTag]

The initial value of the [Symbol.toStringTag] property is the string "WeakRef". This property is used in Object.prototype.toString().

Object.prototype.toString()

The initial value of the [Symbol.toStringTag] property is the string "WeakRef". This property is used in Object.prototype.toString().

WeakRef.prototype.deref()

Returns the WeakRef object's target object, or undefined if the target object has been reclaimed.

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This page was last modified on Jul 10, 2025 by MDN contributors.

[Symbol.hasInstance]()

__defineGetter__()

__defineSetter__()

__lookupGetter__()

__lookupSetter__()

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