当用户在 Chrome 上按下键盘时，如何检测“删除”和“。”？

Question

When I press . it fires the three events, keydown , keypress and keyup .

keydown
  which: 190 == ¾
  keyCode: 190 == ¾

keypress
  which: 46 == .
  keyCode: 46 == .

keyup
  which: 190 == ¾
  keyCode: 190 == ¾

When I press delete it fires two events, keydown and keyup .

keydown
  which: 46 == .
  keyCode: 46 == .

keyup
  which: 46 == .
  keyCode: 46 == .

I want to press . and be able to get the corresponding character ( 46 ==. ). But on keydown and keyup I get 190 which is ¾ . On the keypress I get the correct value, but this event is not fired when I press delete .

When I press delete I get the code 46 on keydown and keyup . But the code 46 is a . and not delete .

How can I make an event to capture both keys and tell the difference, if it was a . pressed or delete key?

Page to test: http://jsfiddle.net/Eg9F3/

Answer 1

I think the best solution would be to map the keys you want ( demo ), then use e.which to cross-reference what key was pressed. There is a good reference of cross-browser keyCode values, which work in this case because jQuery normalizes the e.which value.

var keys = {
  46  : 'del',
  190 : '.'
};

$("textarea").bind('keyup', function(e){
  $('#r').append( 'keyup (' + e.which + '): ' + (keys[e.which] || String.fromCharCode(e.which)) );
});

This is similar to the method that jQuery UI uses - see the keycodes cross-reference at the top of the file? And it is also the method I use in the keycaster plugin.

Answer 2

In fact it's strange but it is logic.

The function String.fromCharCode is working with real char code, not with KB actions (left, delete...)

Why don't filter by keyCode simply?

Answer 3

I've forced the same behavior as Firefox, example on jsFiddle

$("textarea").keydown(function(e) {
    // if the key pressed was found on the list of specialChars
    if (specialChars[e.keyCode])
    {
        // triggers the fake event
        $("textarea").trigger("chromekeypress", e);

        // temporary avoid keypress from firing
        $("textarea").unbind("keypress");
        setTimeout(function(){ $("textarea").bind("keypress", handleKey); },10);
    }
});

$("textarea").keypress(handleKey); // main event

$("textarea").bind("chromekeypress", chromeKeyPress); // chrome workaround

function chromeKeyPress(i,e){
    e.type="chromekeypress";
    e.which = 0; // copy Firefox behavior, which == 0 means a special key pressed
    handleKey(e); // fires the main event
}
function handleKey(e) {

    // which is going to be 0 if it is a special key
    // and keycode will have the code of the special key
    // or
    // which will have the value of the key

    $("#r").html($("#r").html() + "\n" +
        e.type + "\n" +
        "  which: " + e.which + " == " + String.fromCharCode(e.which) + "\n" +
        "  keyCode: " + e.keyCode + " == " + String.fromCharCode(e.keyCode) + "\n" +
     "");
}

Answer 4

The value of "which" in a "keypress" handler does not have the same meaning as that of "which" in a "keydown" or "keyup" handler. In those, it's the keycode for the key on the keyboard, and not a character ordinal. In "keypress" it is the character, but you don't get a "keypress" for Del (as you've noticed).

Thus, that's a different 46 in the "keypress" handler (for ".") than in the "keydown" and "keyup" events for Del .

You probably should use either "keydown" or "keyup" and check for the keycode.