Class WeakMap

• TopLevel.Object
  • TopLevel.WeakMap

The WeakMap is map whose entries are subject to garbage collection if there are no more references to the keys. Keys must be objects (no primitives). Elements can't be iterated.

API Version:

Available from version 21.2.

Property	Description
size: Number	Number of key/value pairs stored in this map.

Constructor	Description
WeakMap()	Creates an empty map.
WeakMap(Iterable)	If the passed value is null or undefined then an empty map is constructed.

Method	Description
clear()	Removes all key/value pairs from this map.
delete(Object)	Removes the entry for the given key.
get(Object)	Returns the value associated with the given key.
has(Object)	Returns if this map has value associated with the given key.
set(Object, Object)	Adds or updates a key/value pair to the map.

assign, create, create, defineProperties, defineProperty, entries, freeze, fromEntries, getOwnPropertyDescriptor, getOwnPropertyNames, getOwnPropertySymbols, getPrototypeOf, hasOwnProperty, is, isExtensible, isFrozen, isPrototypeOf, isSealed, keys, preventExtensions, propertyIsEnumerable, seal, setPrototypeOf, toLocaleString, toString, valueOf, values

size: Number

Number of key/value pairs stored in this map.

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WeakMap()

Creates an empty map.

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WeakMap(values: Iterable)

If the passed value is null or undefined then an empty map is constructed. Else an iterator object is expected that produces a two-element array-like object whose first element is a value that will be used as a Map key and whose second element is the value to associate with that key.

Parameters:

• values - The initial map values

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clear(): void

Removes all key/value pairs from this map.

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delete(key: Object): Boolean

Removes the entry for the given key.

Parameters:

• key - The key of the key/value pair to be removed from the map.

Returns:

• true if the map contained an entry for the passed key that was removed. Else false is returned.

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get(key: Object): Object

Returns the value associated with the given key.

Parameters:

• key - The key to look for.

Returns:

• The value associated with the given key if an entry with the key exists else undefined is returned.

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has(key: Object): Boolean

Returns if this map has value associated with the given key.

Parameters:

• key - The key to look for.

Returns:

• true if an entry with the key exists else false is returned.

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set(key: Object, value: Object): WeakMap

Adds or updates a key/value pair to the map.

Parameters:

• key - The key object.
• value - The value to be associate with the key.

Returns:

• This map object.

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