use promise instead of cb

ui/helpers/utils/export-utils.js

@@ -1,23 +1,24 @@
 import { getRandomFileName } from './util';
 
-function encodeB64(text, cb) {
-  const buf = new TextEncoder().encode(text);
-  // eslint-disable-next-line no-undef
-  const reader = new FileReader();
-  reader.onload = () => cb(reader.result.split(',')[1]);
-  // eslint-disable-next-line no-undef
-  reader.readAsDataURL(new Blob([buf]));
+function encodeB64(text) {
+  return new Promise((resolve) => {
+    const buf = new TextEncoder().encode(text);
+    // eslint-disable-next-line no-undef
+    const reader = new FileReader();
+    reader.onload = () => resolve(reader.result.split(',')[1]);
+    // eslint-disable-next-line no-undef
+    reader.readAsDataURL(new Blob([buf]));
+  });
 }
 
-export function exportAsFile(filename, data, type = 'text/csv') {
-  encodeB64(data, (b64) => {
-    // eslint-disable-next-line no-param-reassign
-    filename = filename || getRandomFileName();
-    const elem = window.document.createElement('a');
-    elem.href = `data:${type};Base64,${b64}`;
-    elem.download = filename;
-    document.body.appendChild(elem);
-    elem.click();
-    document.body.removeChild(elem);
-  });
+export async function exportAsFile(filename, data, type = 'text/csv') {
+  const b64 = await encodeB64(data);
+  // eslint-disable-next-line no-param-reassign
+  filename = filename || getRandomFileName();
+  const elem = window.document.createElement('a');
+  elem.href = `data:${type};Base64,${b64}`;
+  elem.download = filename;
+  document.body.appendChild(elem);
+  elem.click();
+  document.body.removeChild(elem);
 }