fix typescript errors, add tsconfig.json

tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "compilerOptions": {
+    "target": "es2016",                                  /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
+    "jsx": "react",
+    "module": "commonjs",                                /* Specify what module code is generated. */
+    "esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */
+    "forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */
+    /* Type Checking */
+    // "strict": true,                                   /* Enable all strict type-checking options. */
+    "noImplicitAny": false,                              /* Enable error reporting for expressions and declarations with an implied `any` type.. */
+    "skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
+  }
+}

web/src/render.tsx

@@ -25,15 +25,13 @@ require('highlightjs-line-numbers.js');
 
 const FileForm = () => {
   const handleChange = (event: React.ChangeEvent<HTMLInputElement>) => {
+    let file = event.target.files![0];
     const fr = new FileReader();
-    fr.onload = (e) => {
+    fr.onload = (_e) => {
-      const { result } = e.target;
+      let data = new Uint8Array(fr.result as ArrayBuffer);
-      if (result instanceof ArrayBuffer) {
-        let data = new Uint8Array(result);
       encrypt_array_buffer(data);
     }
-    }
+    fr.readAsArrayBuffer(file);
-    fr.readAsArrayBuffer((event.target as HTMLInputElement).files[0]);
   }
 
   return (