support upload csv file

src/main.jsx

@@ -69,6 +69,21 @@ function StringToUtf8CodePoint() {
 function CsvSplit() {
   const [input, setInput] = useState('"a","b","c"\n"1\n10","2","3"');
   const [output, setOutput] = useState([]);
+  const onFileInputChange = useCallback(e=>{
+        if (!e.target.files) return;
+        const fetchFile = async () => {
+
+        const texts = await Promise.all(
+        Array.from( e.target.files).map(async(f) => {
+        const resp = await  fetch(f)
+        return await resp.text()
+        })
+        )
+
+        setInput( texts.join("\n"))
+        }
+        fetchFile()
+        },[setInput] );
   useEffect(() => {
     let shouldUpdate = true;
     parse(input, {}, (err, output) => {
@@ -95,6 +110,7 @@ function CsvSplit() {
           resize: "vertical",
         }}
       />
+      <input type="file" onChange={onFileInputChange} multiple />
       {output instanceof CsvError ? (
         <div>
           {output.code} {output.message}