BunFile.slice

interface BunFile

const file = Bun.file("./hello.json");
console.log(file.type); // "application/json"
console.log(await file.text()); // '{"hello":"world"}'

• lastModified: number

  A UNIX timestamp indicating when the file was last modified.

• readonly name?: string

  The name or path of the file, as specified in the constructor.

• readonly readable: ReadableStream
• readonly size: number

  MDN Reference

• readonly type: string

  MDN Reference

• arrayBuffer(): Promise<ArrayBuffer>

  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) its the same as new Uint8Array(await blob.arrayBuffer())

• delete(): Promise<void>

  Deletes the file (same as unlink)

• exists(): Promise<boolean>

  Does the file exist?

  This returns true for regular files and FIFOs. It returns false for directories. Note that a race condition can occur where the file is deleted or renamed after this is called but before you open it.

  This does a system call to check if the file exists, which can be slow.

  If using this in an HTTP server, it's faster to instead use return new Response(Bun.file(path)) and then an error handler to handle exceptions.

  Instead of checking for a file's existence and then performing the operation, it is faster to just perform the operation and handle the error.

  For empty Blob, this always returns true.

• 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 a application/x-www-form-urlencoded body.

  The type property of the blob is used to determine 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.

• 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.

• slice(begin?: number, end?: number, contentType?: string): BunFile

  Offset any operation on the file starting at begin and ending at end. end is relative to 0

  Similar to TypedArray.subarray. Does not copy the file, open the file, or modify the file.

  If begin > 0, () will be slower on macOS

  @param begin

  start offset in bytes

  @param end

  absolute offset in bytes (relative to 0)

  @param contentType

  MIME type for the new BunFile

  slice(begin?: number, contentType?: string): BunFile

  Offset any operation on the file starting at begin

  Similar to TypedArray.subarray. Does not copy the file, open the file, or modify the file.

  If begin > 0, Bun.write() will be slower on macOS

  @param begin

  start offset in bytes

  @param contentType

  MIME type for the new BunFile

  slice(contentType?: string): BunFile

  Slice the file from the beginning to the end, optionally with a new MIME type.

  @param contentType

  MIME type for the new BunFile

• stat(): Promise<Stats>

  Provides useful information about the file.

• stream(): ReadableStream<Uint8Array<ArrayBufferLike>>

  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

• unlink(): Promise<void>

  Deletes the file.

• write(data: string | ArrayBuffer | SharedArrayBuffer | Request | Response | BunFile | ArrayBufferView<ArrayBufferLike>, options?: { highWaterMark: number }): Promise<number>

  Write data to the file. This is equivalent to using Bun.write with a BunFile.

  @param data

  The data to write.

  @param options

  The options to use for the write.

• writer(options?: { highWaterMark: number }): FileSink

  Incremental writer for files and pipes.