Pressing a button on the keyboard

It also works on Mac:

document.addEventListener("keydown", function(e){
	if (e.keyCode == 83 && (navigator.platform.match("Mac") ? e.metaKey : e.ctrlKey)){
		e.preventDefault();
		alert("CTRL+S pressionado!");
	}
}, false);

Clique aqui e Pressione CTRL+S (para teste)

Use Javascript.

• First recognize which command you want to use.
• Then define a function that will insert this shortcut.
• Finally, call up the desired function.

In this example: Shortcut: (Alt + 'a')

document.onkeyup=function(e){
  var e = e || window.event; // for IE to cover IEs window event-object
  if(e.altKey && e.which == 65) {
    //Chama sua função JS aqui
  }
}

In this website you can pick up which code for each key you want.