Is it possible to use long press for file dialog? For example Long Press in JavaScript? has an answer to trigger an event in long press. However, this can't be used for triggering file input click in most browsers since it is not considered as a user activation.
var pressTimer;
$("a").mouseup(function(){
clearTimeout(pressTimer);
// Clear timeout
return false;
}).mousedown(function(){
// Set timeout
pressTimer = window.setTimeout(function()
{ fileChooser.click() // assume fileChoose is a file input element
// This is suppressed by most browsers.
},1000);
return false;
});