BunFile.slice method | Bun module | Bun

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

start offset in bytes

absolute offset in bytes (relative to 0)

MIME type for the new 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

start offset in bytes

MIME type for the new BunFile

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

MIME type for the new BunFile

Blob powered by the fastest system calls available for operating on files.

This Blob is lazy. That means it won't do any work until you read from it.

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

A UNIX timestamp indicating when the file was last modified.

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

MDN Reference

MDN Reference

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

MDN Reference

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())

Deletes the file (same as unlink)

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.

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.

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");

Read the data from the blob as a JSON object.

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

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

start offset in bytes

absolute offset in bytes (relative to 0)

MIME type for the new 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

start offset in bytes

MIME type for the new BunFile

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

MIME type for the new BunFile

Provides useful information about the file.

MDN Reference

Returns a readable stream of the blob's contents

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

Deletes the file.

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

The data to write.

The options to use for the write.

Incremental writer for files and pipes.