reader.onload = (function(f) {
return function(e) {
// Here you can use `e.target.result` or `this.result`
// and `f.name`.
};
})(file);
const input = document.querySelector("#in");
let file;
input.addEventListener("change", async e => {
file = e.target.files[0];
this.fileContent = await file.text();
});