fetch-base64

Fetch Base64

A node package to retrieve fetch local or remote files in base64 encoding. Useful for embedding assets (images, web fonts, etc.) into HTML or CSS documents.

Disclaimer: I've only used this for images so far, but there is no reason why it should not work for any other kind of file.

If you find a bug please report it here.

TL;DR example

const fetch = require(fetch-base64);

fetch.local('/path/to/image.jpg').then((data) => {
  // data[0] contains the raw base64-encoded jpg
}).catch((reason) => {});

fetch.remote('http://domain.com/to/image.jpg').then((data) => {
  // data[1] contains base64-encoded jpg with MimeType
}).catch((reason) => {});

fecth.auto('/remote/or/local/path/image.gif').then((data) => {

}).catch((reason) => {});

Install

npm install --save fetch-base64

API

Return value

All the functions return a Promise which when resolved will return an Array with two Strings (data):

• data[0] will contain the raw base64-encoded file. E.g.: iVBORw0KGgoAAAANSUhEUg...
• data[1] will contain the same information as data[0] and the mimeType. Useful if you want to embed the file into an HTMl or CSS document. E.g.: data:image/png;base64,iVBORw0KGgoAAAANSUhEUg...

fetch.local(...paths)

Fetch local files and return a promise with the file in base64 format.

Params

• ...paths String(s): Single or multiple paths which will be combined using node's path.resolve(). You can pass multiple paths to resolve a relative path to an absolute path. Some examples of valid values for this parameter:
  • '/some/absolute/path/image.jpg'
  • '/base/path/to/html', './img/animation.gif'

fetch.remote(url)

Fetch remote files and return a promise with the file in base64 format.

User Agent is spoofed to be same as Chrome's to avoid some restrictions, but fetching could still fail for other reasons.

Params

• url String: URL where the image resides. Note that node must have access to the given URL.

fetch.auto(...paths)

This function will try to automatically detect the kind of path passed (remote or local) and invoke the correspondent function.

Params

• ...paths String(s): Accepts the same parameter as fetch.local(). If more than one path is passed, local will be assumed as path concatenation is not supported for remote URLs right now. Some examples of valid values for this parameter:
  • 'http://some.domain/file.png'
  • '/base/path/to/html', './img/animation.gif'
• basePathForRelative String (optional): Only used for fetching local images. See fetch.local documentation above.

Utility functions

fetch.isLocal(path)

Returns true if the passed path (String) is local. Returns false otherwise.

fetch.isRemote(path)

Returns true if the passed path (String) is remote. Returns false otherwise.

Examples

Include package

const fetch = require('fetch-base64');

Local

// will fetch image in /Users/bla/src/project/img/logo.jpg
const doFetchLocal = fetch.local('./img/logo.jpg', '/Users/bla/src/project');
doFetchLocal.then((data) => {
  console.log(`base64 image raw: ${data[0]}`);
}, (reason) => {
  console.log(`Fetch Failed: ${reason}`)
})

Remote

const doFetchRemote = fetch.remote('https://somedomain.com/image.jpg');
doFetchRemote.then((data) => {
  console.log(`base64 image with mimeType: ${data[1]}`);
}, (reason) => {
  console.log(`Fetch Failed: ${reason}`)
})

Auto

const doFetch = fetch.auto('https://somedomain.com/image.jpg');
doFetch.then((data) => {
  console.log(`base 64 image: ${data[0]}`);
}, (reason) => {
  console.log(`Fetch Failed: ${reason}`)
})