fetch-base64
v2.1.2
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A node package to retrieve fetch local or remote files in base64 encoding.
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Fetch Base64
A node package to fetch local or remote files in base64 encoding. Useful for inlining 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 shouldn't work for any other kind of files.
If you find a bug please report it here.
Usage
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 asdata[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'spath.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 file in url
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 file resides. Note that node must have access to the given URL.
fetch.remote(from, to)
Resolve url using node's url.resolve(from, to)
, fetch remote file 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
from
<string>
: The Base URL being resolved against.to
<string>
: The HREF URL being resolved.
See url.resolve()
for more information and examples.
fetch.remote(options)
Advanced version of the fetch.remote
where you can pass an options
object containing:
paths
<[string]>
: Array with 2 Strings representingfrom
andto
(see above).url
<string>
: The url to fetch. If bothpaths
andurl
are passed,paths
takes priority.headers
<object>
: Object containing key-value pairs with the desired HTTP Headers you want to attach to the fetch request.
User Agent will still be spoofed to be same as Chrome.
fetch.auto(...mixed)
This function will do the best effort to automatically detect the kind of path passed (remote
or local
) and invoke the correspondent function.
It will use the fetch.isRemote()
function to determine if a remote url or a local path has been passed in the first parameter.
Params
...mixed
<string(s)>
: Accepts the same parameters asfetch.local(...paths)
,fetch.remote(url)
orfetch.remote(from, to)
- see above. Examples of valid calls:fetch.auto('/base/path/to/html', './img/animation.gif');
fetch.auto('http://some.domain/file.png');
fetch.auto('http://some.domain/', 'file.png');
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('/Users/bla/src/project', './img/logo.jpg');
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}`)
});
const doFetchRemote2 = fetch.remote('https://somedomain.com', '/image.jpg');
doFetchRemote2.then((data) => {
console.log(`base64 image with mimeType: ${data[1]}`);
}, (reason) => {
console.log(`Fetch Failed: ${reason}`)
});
const doFetchRemote = fetch.remote({ url: 'https://somedomain.com/image.jpg', headers: { 'custom-header': 'foo' } });
doFetchRemote.then((data) => {
console.log(`base64 image with mimeType: ${data[1]}`);
}, (reason) => {
console.log(`Fetch Failed: ${reason}`)
});
Auto
const doFetchAuto = fetch.auto('https://somedomain.com/image.jpg');
doFetchAuto.then((data) => {
console.log(`base64 image: ${data[0]}`);
}, (reason) => {
console.log(`Fetch Failed: ${reason}`)
});
const doFetchAuto2 = fetch.auto('/some/local/', '/path/', './image.jpg');
doFetchAuto2.then((data) => {
console.log(`base64 image: ${data[0]}`);
}, (reason) => {
console.log(`Fetch Failed: ${reason}`)
});