> For the complete documentation index, see [llms.txt](https://near-sdk-js.gitbook.io/near-sdk-js/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-map/classes/lookupmap.md).

# LookupMap

[**collections/lookup-map**](/near-sdk-js/collections/lookup-map.md) • **Docs**

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[near-sdk-js v2.0.0](/near-sdk-js/packages.md) / [collections/lookup-map](/near-sdk-js/collections/lookup-map.md) / LookupMap

## Class: LookupMap\<DataType>

A lookup map that stores data in NEAR storage.

### Extends

* [`SubType`](/near-sdk-js/collections/subtype/classes/subtype.md)<`DataType`>

### Type Parameters

• **DataType**

### Constructors

#### new LookupMap()

> **new LookupMap**<`DataType`>(`keyPrefix`): [`LookupMap`](/near-sdk-js/collections/lookup-map/classes/lookupmap.md)<`DataType`>

**Parameters**

• **keyPrefix**: `string`

The byte prefix to use when storing elements inside this collection.

**Returns**

[`LookupMap`](/near-sdk-js/collections/lookup-map/classes/lookupmap.md)<`DataType`>

**Overrides**

[`SubType`](/near-sdk-js/collections/subtype/classes/subtype.md).[`constructor`](/near-sdk-js/collections/subtype/classes/subtype.md#constructors)

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:17](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L17)

### Properties

#### keyPrefix

> `readonly` **keyPrefix**: `string`

The byte prefix to use when storing elements inside this collection.

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:17](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L17)

### Methods

#### containsKey()

> **containsKey**(`key`): `boolean`

Checks whether the collection contains the value.

**Parameters**

• **key**: `string`

The value for which to check the presence.

**Returns**

`boolean`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:26](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L26)

***

#### extend()

> **extend**(`keyValuePairs`, `options`?): `void`

Extends the current collection with the passed in array of key-value pairs.

**Parameters**

• **keyValuePairs**: \[`string`, `DataType`]\[]

The key-value pairs to extend the collection with.

• **options?**: [`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>

Options for storing the data.

**Returns**

`void`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:102](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L102)

***

#### get()

> **get**(`key`, `options`?): `DataType`

Get the data stored at the provided key.

**Parameters**

• **key**: `string`

The key at which to look for the data.

• **options?**: `Omit`<[`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>, `"serializer"`>

Options for retrieving the data.

**Returns**

`DataType`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:37](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L37)

***

#### remove()

> **remove**(`key`, `options`?): `DataType`

Removes and retrieves the element with the provided key.

**Parameters**

• **key**: `string`

The key at which to remove data.

• **options?**: `Omit`<[`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>, `"serializer"`>

Options for retrieving the data.

**Returns**

`DataType`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:57](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L57)

***

#### serialize()

> **serialize**(`options`?): `Uint8Array`

Serialize the collection.

**Parameters**

• **options?**: `Pick`<[`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>, `"serializer"`>

Options for storing the data.

**Returns**

`Uint8Array`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:116](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L116)

***

#### set()

> **set**(`key`, `newValue`, `options`?): `DataType`

Store a new value at the provided key.

**Parameters**

• **key**: `string`

The key at which to store in the collection.

• **newValue**: `DataType`

The value to store in the collection.

• **options?**: [`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>

Options for retrieving and storing the data.

**Returns**

`DataType`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:79](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L79)

***

#### set\_reconstructor()

> **set\_reconstructor**(`options`?): `Omit`<[`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>, `"serializer"`>

**Parameters**

• **options?**: `Omit`<[`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>, `"serializer"`>

**Returns**

`Omit`<[`GetOptions`](/near-sdk-js/types/collections/interfaces/getoptions.md)<`DataType`>, `"serializer"`>

**Inherited from**

[`SubType`](/near-sdk-js/collections/subtype/classes/subtype.md).[`set_reconstructor`](/near-sdk-js/collections/subtype/classes/subtype.md#set_reconstructor)

**Defined in**

[packages/near-sdk-js/src/collections/subtype.ts:8](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/subtype.ts#L8)

***

#### subtype()

> **subtype**(): `any`

**Returns**

`any`

**Inherited from**

[`SubType`](/near-sdk-js/collections/subtype/classes/subtype.md).[`subtype`](/near-sdk-js/collections/subtype/classes/subtype.md#subtype)

**Defined in**

[packages/near-sdk-js/src/collections/subtype.ts:6](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/subtype.ts#L6)

***

#### reconstruct()

> `static` **reconstruct**<`DataType`>(`data`): [`LookupMap`](/near-sdk-js/collections/lookup-map/classes/lookupmap.md)<`DataType`>

Converts the deserialized data from storage to a JavaScript instance of the collection.

**Type Parameters**

• **DataType**

**Parameters**

• **data**: [`LookupMap`](/near-sdk-js/collections/lookup-map/classes/lookupmap.md)<`unknown`>

The deserialized data to create an instance from.

**Returns**

[`LookupMap`](/near-sdk-js/collections/lookup-map/classes/lookupmap.md)<`DataType`>

**Defined in**

[packages/near-sdk-js/src/collections/lookup-map.ts:125](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-map.ts#L125)