refactor: migrate lqip-loader to TS, fix typing for Webpack Loaders (#5779)

packages/lqip-loader/src/lqip.ts

@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import Vibrant from 'node-vibrant';
+import path from 'path';
+import sharp from 'sharp';
+import {toPalette, toBase64} from './utils';
+
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const {version} = require('../package.json');
+
+const ERROR_EXT = `Error: Input file is missing or uses unsupported image format, lqip v${version}`;
+
+const SUPPORTED_MIMES: Record<string, string> = {
+  jpeg: 'image/jpeg',
+  jpg: 'image/jpeg',
+  png: 'image/png',
+};
+
+async function base64(file: string): Promise<string> {
+  let extension = path.extname(file) || '';
+  extension = extension.split('.').pop()!;
+
+  if (!SUPPORTED_MIMES[extension]) {
+    throw new Error(ERROR_EXT);
+  }
+
+  const data = await sharp(file).resize(10).toBuffer();
+  if (data) {
+    return toBase64(SUPPORTED_MIMES[extension], data);
+  }
+  throw new Error('Unhandled promise rejection in base64 promise');
+}
+
+async function palette(file: string): Promise<string[]> {
+  const vibrant = new Vibrant(file, {});
+  const pal = await vibrant.getPalette();
+  if (pal) {
+    return toPalette(pal);
+  }
+  throw new Error(`Unhandled promise rejection in colorPalette ${pal}`);
+}
+
+process.on('unhandledRejection', (up) => {
+  throw up;
+});
+
+export {base64, palette};