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# Interface: UnderlyingSource<R\>

[internal](../modules/internal-10.md).UnderlyingSource

## Type parameters

| Name | Type |
| :------ | :------ |
| `R` | `any` |

## Properties

### autoAllocateChunkSize

• `Optional` **autoAllocateChunkSize**: `number`

#### Defined in

docs-util/node_modules/typescript/lib/lib.dom.d.ts:1961

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### cancel

• `Optional` **cancel**: [`UnderlyingSourceCancelCallback`](internal-10.UnderlyingSourceCancelCallback.md)

#### Defined in

docs-util/node_modules/typescript/lib/lib.dom.d.ts:1962

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### pull

• `Optional` **pull**: [`UnderlyingSourcePullCallback`](internal-10.UnderlyingSourcePullCallback.md)<`R`\>

#### Defined in

docs-util/node_modules/typescript/lib/lib.dom.d.ts:1963

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### start

• `Optional` **start**: [`UnderlyingSourceStartCallback`](internal-10.UnderlyingSourceStartCallback.md)<`R`\>

#### Defined in

docs-util/node_modules/typescript/lib/lib.dom.d.ts:1964

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### type

• `Optional` **type**: ``"bytes"``

#### Defined in

docs-util/node_modules/typescript/lib/lib.dom.d.ts:1965