如何检测是否按下了左 Alt + 字母

Question

I need to perform some action only if the left ALT key was pressed with the letter s . I can find whether some Alt + s pressed using the keydown event, when oEvent.altKey === true and String.fromCharCode(oEvent.keyCode) === 'S' . I can also find whether the left or right ALT was pressed by:

oEvent.originalEvent.location === KeyboardEvent.DOM_KEY_LOCATION_LEFT 

or

oEvent.originalEvent.location === KeyboardEvent.DOM_KEY_LOCATION_RIGHT

But what I could not find is the way to combine the two.

Answer 1

For make this you have to register two events, keyUp and keyDown and using a single variable can do the trick,

 isleftAltPressed : false,

keyUp: function(e)
{
  var keyCode = e.which ? e.which : e.keyCode;
  if(keyCode == 18)
      isleftAltPressed = false;
},

keyDown: function(e)
{
  var keyCode = e.which ? e.which : e.keyCode;

  if(keyCode == 18 && e.originalEvent.location === KeyboardEvent.DOM_KEY_LOCATION_LEFT)
      isleftAltPressed = true;

    if(e.altKey && isleftAltPressed && keyCode == 83)
      alert("hi");

},