👩‍💻 dx: Define Blob from/to DataURL conversion utilities.

imports/lib/blob/blobFromDataURL.ts

@@ -0,0 +1,6 @@
+const blobFromDataURL = async (url: string): Promise<Blob> => {
+	const response = await fetch(url);
+	return response.blob();
+};
+
+export default blobFromDataURL;

imports/lib/blob/blobToDataURL.ts

@@ -0,0 +1,39 @@
+const _blobToDataURLClient = async (blob: Blob): Promise<string> =>
+	new Promise<string>((resolve, reject) => {
+		const reader = new FileReader();
+		reader.addEventListener('load', (_e) => {
+			resolve(reader.result as string);
+		});
+
+		reader.addEventListener('error', (_e) => {
+			reject(reader.error);
+		});
+
+		reader.addEventListener('abort', (_e) => {
+			reject(new Error('Read aborted'));
+		});
+		reader.readAsDataURL(blob);
+	});
+
+const _blobToDataURLServer = async (blob: Blob): Promise<string> => {
+	const mimeType = blob.type;
+	if (mimeType === '') {
+		throw new Error('unknown mime-type');
+	}
+
+	const arrayBuffer = await blob.arrayBuffer();
+
+	const {Buffer} = await import('buffer');
+	const buffer = Buffer.from(arrayBuffer);
+
+	const base64 = buffer.toString('base64');
+
+	const {default: dataURL} = await import('../dataURL');
+	return dataURL(mimeType, base64);
+};
+
+const blobToDataURL = Meteor.isServer
+	? _blobToDataURLServer
+	: _blobToDataURLClient;
+
+export default blobToDataURL;

imports/lib/blob/dataURL.tests.ts

@@ -0,0 +1,26 @@
+// eslint-disable-next-line import/no-unassigned-import
+import 'regenerator-runtime/runtime.js';
+
+import {assert} from 'chai';
+
+import {isomorphic} from '../../_test/fixtures';
+import {randomPNGDataURI} from '../../_test/png';
+
+import blobFromDataURL from './blobFromDataURL';
+import blobToDataURL from './blobToDataURL';
+
+isomorphic(__filename, () => {
+	it('should allow to convert back and forth from a dataURL', async () => {
+		if (Meteor.isServer) {
+			await import('../../../server/polyfill/fetch');
+		}
+
+		const url = randomPNGDataURI();
+
+		const blob = await blobFromDataURL(url);
+		assert.instanceOf(blob, Blob);
+
+		const result = await blobToDataURL(blob);
+		assert.equal(result, url);
+	});
+});