press a key in html

presskey.js

function openf12() {
	var keyboardEvent = document.createEvent("KeyboardEvent");
	var initMethod = typeof keyboardEvent.initKeyboardEvent !== 'undefined' ? "initKeyboardEvent" : "initKeyEvent";


	keyboardEvent[initMethod](
		"keydown", // event type : keydown, keyup, keypress
		true, // bubbles
		true, // cancelable
		window, // viewArg: should be window
		false, // ctrlKeyArg
		false, // altKeyArg
		false, // shiftKeyArg
		false, // metaKeyArg
		123, // keyCodeArg : unsigned long the virtual key code, else 0
		0 // charCodeArgs : unsigned long the Unicode character associated with the depressed key, else 0
	);
	
	document.dispatchEvent(keyboardEvent);
}