Readonly DONEReadonly EMPTYReadonly LOADINGReadonly errorReadonly readyReadonly resultOptional options: boolean | AddEventListenerOptionsOptional options: boolean | AddEventListenerOptionsDispatches a synthetic event event to target and returns true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, and false otherwise.
Optional encoding: stringOptional options: boolean | EventListenerOptionsOptional options: boolean | EventListenerOptions
Lets web applications asynchronously read the contents of files (or raw data buffers) stored on the user's computer, using File or Blob objects to specify the file or data to read.
MDN Reference