This is how my input tag looks like:
I typically reset my file input after capturing the selected files. No need to push a button, you have everything required in the $event object that you're passing to onChange:
onChange(event) {
// Get your files
const files: FileList = event.target.files;
// Clear the input
event.srcElement.value = null;
}
Different workflow, but the OP doesn't mention pushing a button is a requirement...