javascript - detect ctrl key pressed or up, keypress event doesn't trigger

I see some similar questions here (like https://stackoverflow.com/questions/6806271/javascript-check-if-ctrl-button-was-pressed) but my problem is actually the event triggering. My js code:

    // Listen to keyboard. 
    window.onkeypress = listenToTheKey;
    window.onkeyup = listenToKeyUp;
            
    /*
        Gets the key pressed and send a request to the associated function
        @input key
    */
    function listenToTheKey(e)
	{
		if (editFlag == 0)
		{
			// If delete key is pressed calls delete
            if (e.keyCode == 46)
				deleteNode();
            
            // If insert key is pressed calls add blank
            if (e.keyCode == 45)
                createBlank();
            
            if (e.keyCode == 17)
                ctrlFlag = 1;
        }
    }

The event triggers for any other keys except the ctrl.
I need to also trigger it for ctrl.
I can't use jQuery/prototype/whatever so those solutions are not acceptable.

So... how can I detect the ctrl?

Try using if (e.ctrlKey).

MDN: event.ctrlKey

Using onkeydown rather than onkeypress may help.

From http://www.w3schools.com/jsref/event_onkeypress.asp

> Note: The onkeypress event is not fired for all keys (e.g. ALT, CTRL, > SHIFT, ESC) in all browsers. To detect only whether the user has > pressed a key, use the onkeydown event instead, because it works for > all keys.

Your event has a property named ctrlKey. You can check this to look if the key was pressed or not. See snippet below for more control like keys.

function detectspecialkeys(e){
    var evtobj=window.event? event : e
    if (evtobj.altKey || evtobj.ctrlKey || evtobj.shiftKey)
        alert("you pressed one of the 'Alt', 'Ctrl', or 'Shift' keys")
}
document.onkeypress=detectspecialkeys