Examples: Add multimodal app (#2328)

examples/multimodal-demo/src/utils/fileUtils.ts

@@ -0,0 +1,16 @@
+import { Buffer } from 'buffer';
+
+export const convertToBase64 = (file: File): Promise<string> => {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader();
+    reader.readAsDataURL(file);
+    reader.onload = () => resolve(reader.result as string);
+    reader.onerror = error => reject(error);
+  });
+};
+
+export const getFileBuffer = async (file: File): Promise<Buffer> => {
+  const response = await fetch(URL.createObjectURL(file));
+  const arrayBuffer = await response.arrayBuffer();
+  return Buffer.from(arrayBuffer);
+};