Answers for "property 'file' does not exist on type 'eventtarget'"

Property 'value' does not exist on type 'EventTarget & Element'.

(e.target as HTMLButtonElement).value

Property 'result' does not exist on type 'EventTarget'

const fileReader: FileReader = new FileReader();

fileReader.onload = (event: Event) => {
   event.target.result; // This is invalid
   fileReader.result; // This is valid
};