# LookupSet

[**collections/lookup-set**](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set) • **Docs**

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[near-sdk-js v2.0.0](https://near-sdk-js.gitbook.io/near-sdk-js/packages) / [collections/lookup-set](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set) / LookupSet

## Class: LookupSet\<DataType>

A lookup set collection that stores entries in NEAR storage.

### Type Parameters

• **DataType**

### Constructors

#### new LookupSet()

> **new LookupSet**<`DataType`>(`keyPrefix`): [`LookupSet`](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set/classes/lookupset)<`DataType`>

**Parameters**

• **keyPrefix**: `string`

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

**Returns**

[`LookupSet`](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set/classes/lookupset)<`DataType`>

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:12](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L12)

### 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-set.ts:12](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L12)

### Methods

#### contains()

> **contains**(`key`, `options`?): `boolean`

Checks whether the collection contains the value.

**Parameters**

• **key**: `DataType`

The value for which to check the presence.

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

Options for storing data.

**Returns**

`boolean`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:20](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L20)

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#### extend()

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

Extends the current collection with the passed in array of elements.

**Parameters**

• **keys**: `DataType`\[]

The elements to extend the collection with.

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

Options for storing the data.

**Returns**

`void`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:63](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L63)

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#### remove()

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

Returns true if the element was present in the set.

**Parameters**

• **key**: `DataType`

The entry to remove.

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

Options for storing data.

**Returns**

`boolean`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:34](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L34)

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#### serialize()

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

Serialize the collection.

**Parameters**

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

Options for storing the data.

**Returns**

`Uint8Array`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:75](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L75)

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#### set()

> **set**(`key`, `options`?): `boolean`

If the set did not have this value present, `true` is returned. If the set did have this value present, `false` is returned.

**Parameters**

• **key**: `DataType`

The value to store in the collection.

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

Options for storing the data.

**Returns**

`boolean`

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:49](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L49)

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#### reconstruct()

> `static` **reconstruct**<`DataType`>(`data`): [`LookupSet`](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set/classes/lookupset)<`DataType`>

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

**Type Parameters**

• **DataType**

**Parameters**

• **data**: [`LookupSet`](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set/classes/lookupset)<`unknown`>

The deserialized data to create an instance from.

**Returns**

[`LookupSet`](https://near-sdk-js.gitbook.io/near-sdk-js/collections/lookup-set/classes/lookupset)<`DataType`>

**Defined in**

[packages/near-sdk-js/src/collections/lookup-set.ts:84](https://github.com/near/near-sdk-js/blob/b58ac04fc6dff2f1120e9098c0cb059493486598/packages/near-sdk-js/src/collections/lookup-set.ts#L84)