How to know if .keyup() is a character key (jQuery)

Question

How to know if .keyup() is a character key (jQuery)

$("input").keyup(function() {

if (key is a character) { //such as a b A b c 5 3 2 $ # ^ ! ^ * # ...etc not enter key or shift or Esc or space ...etc
/* Do stuff */
}

});

Answer 1

You can't do this reliably with the keyup event. If you want to know something about the character that was typed, you have to use the keypress event instead.

The following example will work all the time in most browsers but there are some edge cases that you should be aware of. For what is in my view the definitive guide on this, see http://unixpapa.com/js/key.html.

$("input").keypress(function(e) {
    if (e.which !== 0) {
        alert("Charcter was typed. It was: " + String.fromCharCode(e.which));
    }
});

keyup and keydown give you information about the physical key that was pressed. On standard US/UK keyboards in their standard layouts, it looks like there is a correlation between the keyCode property of these events and the character they represent. However, this is not reliable: different keyboard layouts will have different mappings.

Answer 2

Note: In hindsight this was a quick and dirty answer, and may not work in all situations. To have a reliable solution, see Tim Down's answer (copy pasting that here as this answer is still getting views and upvotes):

You can't do this reliably with the keyup event. If you want to know something about the character that was typed, you have to use the keypress event instead.

The following example will work all the time in most browsers but there are some edge cases that you should be aware of. For what is in my view the definitive guide on this, see http://unixpapa.com/js/key.html.

$("input").keypress(function(e) {
    if (e.which !== 0) {
        alert("Character was typed. It was: " + String.fromCharCode(e.which));
    }
});

keyup and keydown give you information about the physical key that was pressed. On standard US/UK keyboards in their standard layouts, it looks like there is a correlation between the keyCode property of these events and the character they represent. However, this is not reliable: different keyboard layouts will have different mappings.

---

The following was the original answer, but is not correct and may not work reliably in all situations.

To match the keycode with a word character (eg., a would match. space would not)

$("input").keyup(function(event)
{ 
    var c= String.fromCharCode(event.keyCode);
    var isWordcharacter = c.match(/\w/);
}); 

Ok, that was a quick answer. The approach is the same, but beware of keycode issues, see this article in quirksmode.

Answer 3

I'm not totally satisfied with the other answers given. They've all got some kind of flaw to them.

Using keyPress with event.which is unreliable because you can't catch a backspace or a delete (as mentioned by Tarl). Using keyDown (as in Niva's and Tarl's answers) is a bit better, but the solution is flawed because it attempts to use event.keyCode with String.fromCharCode() (keyCode and charCode are not the same!).

However, what we DO have with the keydown or keyup event is the actual key that was pressed (event.key). As far as I can tell, any key with a length of 1 is a character (number or letter) regardless of which language keyboard you're using. Please correct me if that's not true!

Then there's that very long answer from asdf. That might work perfectly, but it seems like overkill.

---

So here's a simple solution that will catch all characters, backspace, and delete. (Note: either keyup or keydown will work here, but keypress will not)

$("input").keydown(function(event) {

    var isWordCharacter = event.key.length === 1;
    var isBackspaceOrDelete = event.keyCode === 8 || event.keyCode === 46;

    if (isWordCharacter || isBackspaceOrDelete) {
        // do something
    }
});

Answer 4

This helped for me:

$("#input").keyup(function(event) {
        //use keyup instead keypress because:
        //- keypress will not work on backspace and delete
        //- keypress is called before the character is added to the textfield (at least in google chrome) 
        var searchText = $.trim($("#input").val());

        var c= String.fromCharCode(event.keyCode);
        var isWordCharacter = c.match(/\w/);
        var isBackspaceOrDelete = (event.keyCode == 8 || event.keyCode == 46);

        // trigger only on word characters, backspace or delete and an entry size of at least 3 characters
        if((isWordCharacter || isBackspaceOrDelete) && searchText.length > 2)
        { ...

Answer 5

I wanted to do exactly this, and I thought of a solution involving both the keyup and the keypress events.

(I haven't tested it in all browsers, but I used the information compiled at http://unixpapa.com/js/key.html)

Edit: rewrote it as a jQuery plugin.

(function($) {
    $.fn.normalkeypress = function(onNormal, onSpecial) {
        this.bind('keydown keypress keyup', (function() {
            var keyDown = {}, // keep track of which buttons have been pressed
                lastKeyDown;
            return function(event) {
                if (event.type == 'keydown') {
                    keyDown[lastKeyDown = event.keyCode] = false;
                    return;
                }
                if (event.type == 'keypress') {
                    keyDown[lastKeyDown] = event; // this keydown also triggered a keypress
                    return;
                }

                // 'keyup' event
                var keyPress = keyDown[event.keyCode];
                if ( keyPress &&
                     ( ( ( keyPress.which >= 32 // not a control character
                           //|| keyPress.which == 8  || // \b
                           //|| keyPress.which == 9  || // \t
                           //|| keyPress.which == 10 || // \n
                           //|| keyPress.which == 13    // \r
                           ) &&
                         !( keyPress.which >= 63232 && keyPress.which <= 63247 ) && // not special character in WebKit < 525
                         !( keyPress.which == 63273 )                            && //
                         !( keyPress.which >= 63275 && keyPress.which <= 63277 ) && //
                         !( keyPress.which === event.keyCode && // not End / Home / Insert / Delete (i.e. in Opera < 10.50)
                            ( keyPress.which == 35  || // End
                              keyPress.which == 36  || // Home
                              keyPress.which == 45  || // Insert
                              keyPress.which == 46  || // Delete
                              keyPress.which == 144    // Num Lock
                              )
                            )
                         ) ||
                       keyPress.which === undefined // normal character in IE < 9.0
                       ) &&
                     keyPress.charCode !== 0 // not special character in Konqueror 4.3
                     ) {

                    // Normal character
                    if (onNormal) onNormal.call(this, keyPress, event);
                } else {
                    // Special character
                    if (onSpecial) onSpecial.call(this, event);
                }
                delete keyDown[event.keyCode];
            };
        })());
    };
})(jQuery);

Answer 6

If you only need to exclude out enter, escape and spacebar keys, you can do the following:

$("#text1").keyup(function(event) {
if (event.keyCode != '13' && event.keyCode != '27' && event.keyCode != '32') {
     alert('test');
   }
});

See it actions here.

You can refer to the complete list of keycode here for your further modification.

Answer 7

I never liked the key code validation. My approach was to see if the input have text (any character), confirming that the user is entering text and no other characters

$('#input').on('keyup', function() {
    var words = $(this).val();
    // if input is empty, remove the word count data and return
    if(!words.length) {
        $(this).removeData('wcount');
        return true;
    }
    // if word count data equals the count of the input, return
    if(typeof $(this).data('wcount') !== "undefined" && ($(this).data('wcount') == words.length)){
        return true;
    }
    // update or initialize the word count data
    $(this).data('wcount', words.length);
    console.log('user tiped ' + words);
    // do you stuff...
});

<html lang="en">
  <head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  </head>
  <body>
  <input type="text" name="input" id="input">
  </body>
</html>