Chrome extension: adding a keyboard shortcut with Alt with addEventListener('keypress')

Question

I am doing this open source chrome extension and I would like to add a shortcut so that when the extension is open and I press Alt+C , then the content of a div is copied to my clipboard.

I am able to add shortcuts with a simple addEventListener :

var inputText = document.getElementById('textareaSource');
    inputText.addEventListener('keypress', function (e) {
        if (e.keyCode == 99) {        
            // alert("You pressed C!");
        }
});

But apparently this way of adding shortcut doesn't allow shortcuts containing Alt . I tried this but I didn't get any alert:

if (e.altKey || e.ctrlKey || e.shiftKey)
    alert("you pressed one of the 'Alt', 'Ctrl', or 'Shift' keys")
}

I am also able to add shortcuts via manifest / background.js (following this and this ). This time, the Alt+C works but it can be triggered everywhere on Chrome and not only when my extension is opened.

Is there a way to get a middle ground: adding a shortcut containing Alt that is only triggered when my extension is opened?

Answer 1

The keypress event won't fire when a modifier key has been pressed, additionally, now it is deprecated.

As it say on the MDN , you should consider using keydown event instead, which supports the way you've tried.

event.keyCode is also deprecated, and event.key should be used instead.

So this code should work:

var inputText = document.getElementById('textareaSource');
    inputText.addEventListener('keydown', function (e) {
        if (e.key == "c" && e.altKey) {        
            // alert("You pressed Alt + C!");
        }
});