Enable async callback function for CSVDownloader ( #146 )

Author: Bunlong

README.md

@@ -713,7 +713,7 @@ export default function CSVDownloader() {
 
 #### Data as a Function/Callback
 
-`data={}` can be a function that returns a data object.
+`data={}` can be a synchronous or asynchronous function that returns a data object.
 
 ```javascript
 import React from 'react';

src/useCSVDownloader.tsx

@@ -28,13 +28,13 @@ function useCSVDownloaderComponent() {
     bom = false,
     config = {},
   }: Props) => {
-    const download = () => {
+    const download = async () => {
       const bomCode = bom ? '\ufeff' : '';
       let csvContent = null;
       let csvURL = null;
 
       if (typeof data === 'function') {
-        data = data();
+        data = await data();
       }
 
       if (typeof data === 'object') {