generic-filehandle2

generic-filehandle2

Provides a uniform interface for accessing binary data from local files, remote HTTP resources, and Blob data in the browser.

Usage

import { LocalFile, RemoteFile, BlobFile } from 'generic-filehandle2'

// operate on a local file path
const local = new LocalFile('/some/file/path/file.txt')

// operate on a remote file path
const remote = new RemoteFile('http://somesite.com/file.txt')

// operate on blob objects
const blobfile = new BlobFile(new Blob([some_data], { type: 'text/plain' }))

// read slice of file, works on remote files with range request
const buf1 = await remote.read(10, 10)
// read whole file
const buf2 = await remote.readFile()

Important: under node.js, you should supply a fetch function to the RemoteFile constructor

import { RemoteFile } from 'generic-filehandle2'
import fetch from 'node-fetch'
const remote = new RemoteFile('http://somesite.com/file.txt', { fetch })

API

async read(length: number, position: number=0, opts?: Options): Promise<Uint8Array>

• length - a length of data to read
• position - the byte offset in the file to read from
• opts - optional Options object

Returns a Promise for the Uint8Array

async readFile(opts?: Options): Promise<Uint8Array | string>

Returns a Promise for Uint8Array or string containing the contents of the whole file.

async stat() : Promise<{size: number}>

Returns a Promise for an object containing as much information about the file as is available. At minimum, the size of the file will be present.

Options

The Options object for the constructor, read and readFile can contain abort signal to customize behavior. All entries are optional.

• signal <AbortSignal> - an AbortSignal that is passed to remote file fetch() API or other file readers
• headers <Object <string, string> >- extra HTTP headers to pass to remote file fetch() API
• overrides <Object> - extra parameters to pass to the remote file fetch() API
• fetch <Function> - a custom fetch callback, otherwise defaults to the environment (initialized in constructor)
• encoding <string> - if specified, then this function returns a string. Otherwise it returns a Uint8Array. Currently only utf8 encoding is supported.

The Options object for readFile can also contain an entry encoding. The default is no encoding, in which case the file contents are returned as a Uint8Array. Currently, the only available encoding is utf8, and specifying that will cause the file contents to be returned as a string. For compatibility with the Node API, the readFile method will accept the string "utf8" instead of an Options object.

References

This module attempts to modernize the original generic-filehandle API by not requiring node.js Buffer polyfill, and in doing so disconnected somewhat with the true Node.js fs API https://github.com/GMOD/generic-filehandle