A cross-browser polyfill for File
A well known issue with the JavaScript File class is the lack of a constructor in some browsers:
new File(['Hi!'], 'file.txt'); // will throw in Edge and Internet ExplorerUsing feature detection, this package will either expose a File polyfill in browsers lacking a proper constructor, or the native File class in others.
You can safely use this package as a drop-in replacement for the native File class in all browsers, e.g.:
import FilePolyfill from '@tanker/file-polyfill';
// Get bits from whatever method you want, using fetch() as an example
const response = await fetch('https://your.server.com/path/to/a/dummy.pdf');
const bits = [await response.arrayBuffer()];
// Construct a file in a cross-browser fashion
const file = new FilePolyfill(bits, 'dummy.pdf', { type: 'application/pdf' });
// Check what we've got
file instanceof window.Blob; // true
file instanceof window.File; // true
file instanceof FilePolyfill; // true
file.name; // 'dummy.pdf'
file.type; // 'application/pdf'
file.size; // the size of dummy.pdfNote that the polyfill is built with a clever class hierarchy so that instances will appear as regular File and Blob instances, that can be used with FileReader and other APIs working with files.
Sponsored by Tanker.