function

fs.openAsBlob

function openAsBlob(
path: PathLike,
options?: OpenAsBlobOptions
): Promise<Blob>;

Returns a Blob whose data is backed by the given file.

The file must not be modified after the Blob is created. Any modifications will cause reading the Blob data to fail with a DOMException error. Synchronous stat operations on the file when the Blob is created, and before each read in order to detect whether the file data has been modified on disk.

import { openAsBlob } from 'node:fs';

const blob = await openAsBlob('the.file.txt');
const ab = await blob.arrayBuffer();
blob.stream();

Referenced types

type PathLike = string | Buffer | URL

Valid types for path values in "fs".

interface OpenAsBlobOptions

  • type?: string

    An optional mime type for the blob.

class Blob

A file-like object of immutable, raw data. Blobs represent data that isn't necessarily in a JavaScript-native format. The File interface is based on Blob, inheriting blob functionality and expanding it to support files on the user's system.

MDN Reference

  • readonly size: number
  • readonly type: string

  • Returns a promise that resolves to the contents of the blob as an ArrayBuffer

  • bytes(): Promise<Uint8Array<ArrayBufferLike>>;

    Returns a promise that resolves to the contents of the blob as a Uint8Array (array of bytes). Equivalent to new Uint8Array(await blob.arrayBuffer())

  • formData(): Promise<FormData>;

    Read the data from the blob as a FormData object.

    This first decodes the data from UTF-8, then parses it as a multipart/form-data body or an application/x-www-form-urlencoded body.

    The blob's type property determines the format of the body.

    This is a non-standard addition to the Blob API, to make it conform more closely to the BodyMixin API.

  • options?: ConstructorOptions
    ): Image;

    Wrap this blob in a Bun.Image pipeline. Equivalent to new Bun.Image(this, options) — the constructor is synchronous (the underlying read happens lazily when an Image terminal is awaited), so this works on Bun.file(), Bun.s3(), fd-backed and in-memory blobs alike:

    await Bun.file("photo.jpg").image().resize(400).webp().write("thumb.webp");
  • json(): Promise<any>;

    Read the data from the blob as a JSON object.

    This first decodes the data from UTF-8, then parses it as JSON.

  • start?: number,
    end?: number,
    contentType?: string
    ): Blob;

    Returns a new Blob with the bytes from start up to but not including end. Negative indices count from the end.

    @param start

    byte offset to start at. Defaults to 0.

    @param end

    byte offset to stop at. Defaults to size.

    @param contentType

    the type of the new Blob.

  • Returns a readable stream of the blob's contents

  • text(): Promise<string>;

    Returns a promise that resolves to the contents of the blob as a string