Can javascript tell the difference between left an

问题:

Mostly this is a sanity check. The key code for both shift keys is 16. Does that mean it is actually impossible to distinguish a left and right shift events in a browser?

回答1:

In newer browsers supporting DOM3 you can use event.location to check the location.

In the DOM3 spec, there are 4 constants defined for location, DOM_KEY_LOCATION_STANDARD, DOM_KEY_LOCATION_LEFT, DOM_KEY_LOCATION_RIGHT, andDOM_KEY_LOCATION_NUMPAD.

In this case, you can do:

if (event.location === KeyboardEvent.DOM_KEY_LOCATION_LEFT){

} else if (event.location === KeyboardEvent.DOM_KEY_LOCATION_RIGHT){

}

回答2:

Internet explorer is capable of distinguishing left and right shift with the shiftLeft property:

shiftLeft property (event)

Otherwise, they are indistinguishable.

回答3:

You can use event.code (the physical keyboard string) instead of event.key (the numeric ascii value).

event.code MDN docs

The KeyboardEvent.code property represents a physical key on the keyboard (as opposed to the character generated by pressing the key).

If you scroll down to "Code values" at the bottom, you can find the two distinct shift keys:

"ShiftLeft", "ShiftRight"

回答4:

The easiest way to do it

$(document).ready(function(){
  $("html").keydown(function(e) {

      if (e.shiftKey) {
         if (event.location == 1) console.log('left shift');
         if (event.location == 2) console.log('right shift');
      }

  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Note: You have to click the inside white space when you run code snippet to activate keyboard keys. This is tested in Chrome and Safari.