170

This is what I have now:

$("input").bind("keydown",function(e){
    var value = this.value + String.fromCharCode(e.keyCode);
}

If the e.keyCode may not be an ASCII character (Alt, backspace, del, arrows, etc.)... I would now need to trim these values from value somehow (preferably programmatically - not with lookup tables).

I'm using jQuery.

I must use the keydown event. keyPress doesn't activate for certain keys I need to capture (Esc, del, backspace, etc.).

I cannot use setTimeout to get the input's value. setTimeout(function(){},0) is too slow.

Remi Guan
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David Murdoch
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    You must use `keydown` to capture character codes? You're in for a hell of a ride: http://www.quirksmode.org/js/keys.html (hint: **use `keypress`!!**) – Crescent Fresh Nov 20 '09 at 17:52
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    The case of the character doesn't matter. And I need to capture up,down,left,right,esc,del,backspace for at least FF and IE; so keypress is out of the question. Thanks for the hint though. :-) – David Murdoch Nov 20 '09 at 18:06
  • In response to this problem I just wrote a jQuery plugin: https://github.com/bpeacock/key-to-charCode/ It is a bit down and dirty and could be better integrated into jQuery, but it's a start. – Brian Peacock Apr 03 '13 at 23:40
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    For anyone that came here trying to solve the KeyCode problem but really just wants to see what key was pressed, check out [this answer](https://stackoverflow.com/a/46060900/1717828). TLDR: `document.onkeydown = function(e){ console.log('Key: ' + e.key); }` – user1717828 Jan 15 '19 at 20:05
  • `keypress` is deprecated and should never be used according to MDN (https://developer.mozilla.org/en-US/docs/Web/API/Element/keypress_event). You should always use `keydown` instead. `keydown` now passes `key` which "Returns a string representing the key value of the key represented by the event." - which is similar to what `keypress` used to do. Read more about the `keydown` event on MDN: https://developer.mozilla.org/en-US/docs/Web/API/Element/keydown_event – OOPS Studio Mar 26 '23 at 01:10

10 Answers10

207

In my experience String.fromCharCode(e.keyCode) is unreliable. String.fromCharCode expects unicode charcodes as an argument; e.keyCode returns javascript keycodes. Javascript keycodes and unicode charcodes are not the same thing! In particular, the numberpad keys return a different keycode from the ordinary number keys (since they are different keys) while the same keycode is returned for both upper and lowercase letters (you pressed the same key in both cases), despite them having different charcodes.

For example, the ordinary number key 1 generates an event with keycode 49 while numberpad key 1 (with Numlock on) generates keycode 97. Used with String.fromCharCode we get the following:

String.fromCharCode(49) returns "1"
String.fromCharCode(97) returns "a"

String.fromCharCode expects unicode charcodes, not javascript keycodes. The key a generates an event with a keycode of 65, independentant of the case of the character it would generate (there is also a modifier for if the Shift key is pressed, etc. in the event). The character a has a unicode charcode of 61 while the character A has a charcode of 41 (according to, for example, http://www.utf8-chartable.de/). However, those are hex values, converting to decimal gives us a charcode of 65 for "A" and 97 for "a".[1] This is consistent with what we get from String.fromCharCode for these values.

My own requirement was limited to processing numbers and ordinary letters (accepting or rejecting depending on the position in the string) and letting control characters (F-keys, Ctrl-something) through. Thus I can check for the control characters, if it's not a control character I check against a range and only then do I need to get the actual character. Given I'm not worried about case (I change all letters to uppercase anyway) and have already limited the range of keycodes, I only have to worry about the numberpad keys. The following suffices for that:

String.fromCharCode((96 <= key && key <= 105)? key-48 : key)

More generally, a function to reliably return the character from a charcode would be great (maybe as a jQuery plugin), but I don't have time to write it just now. Sorry.

I'd also mention e.which (if you're using jQuery) which normalizes e.keyCode and e.charCode, so that you don't need to worry about what sort of key was pressed. The problem with combining it with String.fromCharCode remains.

[1] I was confused for a while -. all the docs say that String.fromCharCode expects a unicode charcode, while in practice it seemed to work for ASCII charcodes, but that was I think due to the need to convert to decimal from hex, combined with the fact that ASCII charcodes and unicode decimal charcodes overlap for ordinary latin letters.

Jonatas Walker
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Adam
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    This comment pretty much sovled all my problems. It's amazing to me that jQuery has not implemented a "fromKeyCode" equivalent to javascript's "String.fromCharCode" – Chris J Jun 06 '12 at 22:52
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    It seems that the KeyPress event does this. See http://stackoverflow.com/a/9350415/209568. From the jQuery docs "Note that keydown and keyup provide a code indicating which key is pressed, while keypress indicates which character was entered. For example, a lowercase "a" will be reported as 65 by keydown and keyup, but as 97 by keypress. An uppercase "A" is reported as 65 by all events. Because of this distinction, when catching special keystrokes such as arrow keys, .keydown() or .keyup() is a better choice." – Adam Jun 28 '12 at 12:37
  • This is most unpleasant for those of us who are addicted to keydown. – Isaac Bolinger Jan 25 '15 at 17:53
  • A note on that last bit about ASCII and Unicode. Unicode has all 128 ASCII characters in the same place. This was intentional so that any file originally encoded as ASCII can masquerade as (and be converted to) Unicode with no work required. Extended ASCII characters are not in the same place though, so if you used those characters you're out of luck. – DanielM Apr 16 '15 at 19:28
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    The point of `keyCode` is to know what key was pressed, not to know what character to use. For instance, "U" on a Dvorak keyboard has the same keycode as "F" on a QWERTY keyboard or "ㄹ" on a Korean keyboard etc. The point is not to convert it into a character, it is there so that you can easily map things to a keyboard position. – Vincent McNabb Jan 19 '18 at 19:44
170

Maybe I didn't understand the question correctly, but can you not use keyup if you want to capture both inputs?

$("input").bind("keyup",function(e){
    var value = this.value + String.fromCharCode(e.keyCode);
});
falgranado
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David Hellsing
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    That doesn't work with other locales which are outside of the ASCII range (such as latin-1 for instance, german, french, italian and spanish if you must know). Also fails for non printable keys, obviously. – Florian Bösch Jan 29 '13 at 12:41
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    This also fails when using numbers on the number pad, e.keyCode is not the ASCII (or even UTF-x) code. – Tom Chiverton Jan 06 '14 at 09:38
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    Bad answer, it doesn't even work with basic characters. Semicolon keyCode , for example, is 186, run a String.fromCharCode() on it and you will get garbage. The problem is that keyCode does not correspond to ASCII for all characters. The ASCII character for semicolon is 59. Same issue is true of every special character, keyCode does NOT return the right code for String.fromCharCode(). – Alexander Tsepkov Feb 04 '17 at 09:06
94

Readable key names indexed by key code

There are relatively few key codes so I simply listed all the corresponding values in a static array so I could simply convert the number 65 into A using keyboardMap[65]

Not all key codes map to a printable character so some other identifiable string is returned.

You may need to modify the array to suit your needs and can simply return empty strings for all the characters you don't care to translate. The following array allows me to quickly and reliably determine which key was pressed in any environment. Enjoy!

// names of known key codes (0-255)

var keyboardMap = [
  "", // [0]
  "", // [1]
  "", // [2]
  "CANCEL", // [3]
  "", // [4]
  "", // [5]
  "HELP", // [6]
  "", // [7]
  "BACK_SPACE", // [8]
  "TAB", // [9]
  "", // [10]
  "", // [11]
  "CLEAR", // [12]
  "ENTER", // [13]
  "ENTER_SPECIAL", // [14]
  "", // [15]
  "SHIFT", // [16]
  "CONTROL", // [17]
  "ALT", // [18]
  "PAUSE", // [19]
  "CAPS_LOCK", // [20]
  "KANA", // [21]
  "EISU", // [22]
  "JUNJA", // [23]
  "FINAL", // [24]
  "HANJA", // [25]
  "", // [26]
  "ESCAPE", // [27]
  "CONVERT", // [28]
  "NONCONVERT", // [29]
  "ACCEPT", // [30]
  "MODECHANGE", // [31]
  "SPACE", // [32]
  "PAGE_UP", // [33]
  "PAGE_DOWN", // [34]
  "END", // [35]
  "HOME", // [36]
  "LEFT", // [37]
  "UP", // [38]
  "RIGHT", // [39]
  "DOWN", // [40]
  "SELECT", // [41]
  "PRINT", // [42]
  "EXECUTE", // [43]
  "PRINTSCREEN", // [44]
  "INSERT", // [45]
  "DELETE", // [46]
  "", // [47]
  "0", // [48]
  "1", // [49]
  "2", // [50]
  "3", // [51]
  "4", // [52]
  "5", // [53]
  "6", // [54]
  "7", // [55]
  "8", // [56]
  "9", // [57]
  "COLON", // [58]
  "SEMICOLON", // [59]
  "LESS_THAN", // [60]
  "EQUALS", // [61]
  "GREATER_THAN", // [62]
  "QUESTION_MARK", // [63]
  "AT", // [64]
  "A", // [65]
  "B", // [66]
  "C", // [67]
  "D", // [68]
  "E", // [69]
  "F", // [70]
  "G", // [71]
  "H", // [72]
  "I", // [73]
  "J", // [74]
  "K", // [75]
  "L", // [76]
  "M", // [77]
  "N", // [78]
  "O", // [79]
  "P", // [80]
  "Q", // [81]
  "R", // [82]
  "S", // [83]
  "T", // [84]
  "U", // [85]
  "V", // [86]
  "W", // [87]
  "X", // [88]
  "Y", // [89]
  "Z", // [90]
  "OS_KEY", // [91] Windows Key (Windows) or Command Key (Mac)
  "", // [92]
  "CONTEXT_MENU", // [93]
  "", // [94]
  "SLEEP", // [95]
  "NUMPAD0", // [96]
  "NUMPAD1", // [97]
  "NUMPAD2", // [98]
  "NUMPAD3", // [99]
  "NUMPAD4", // [100]
  "NUMPAD5", // [101]
  "NUMPAD6", // [102]
  "NUMPAD7", // [103]
  "NUMPAD8", // [104]
  "NUMPAD9", // [105]
  "MULTIPLY", // [106]
  "ADD", // [107]
  "SEPARATOR", // [108]
  "SUBTRACT", // [109]
  "DECIMAL", // [110]
  "DIVIDE", // [111]
  "F1", // [112]
  "F2", // [113]
  "F3", // [114]
  "F4", // [115]
  "F5", // [116]
  "F6", // [117]
  "F7", // [118]
  "F8", // [119]
  "F9", // [120]
  "F10", // [121]
  "F11", // [122]
  "F12", // [123]
  "F13", // [124]
  "F14", // [125]
  "F15", // [126]
  "F16", // [127]
  "F17", // [128]
  "F18", // [129]
  "F19", // [130]
  "F20", // [131]
  "F21", // [132]
  "F22", // [133]
  "F23", // [134]
  "F24", // [135]
  "", // [136]
  "", // [137]
  "", // [138]
  "", // [139]
  "", // [140]
  "", // [141]
  "", // [142]
  "", // [143]
  "NUM_LOCK", // [144]
  "SCROLL_LOCK", // [145]
  "WIN_OEM_FJ_JISHO", // [146]
  "WIN_OEM_FJ_MASSHOU", // [147]
  "WIN_OEM_FJ_TOUROKU", // [148]
  "WIN_OEM_FJ_LOYA", // [149]
  "WIN_OEM_FJ_ROYA", // [150]
  "", // [151]
  "", // [152]
  "", // [153]
  "", // [154]
  "", // [155]
  "", // [156]
  "", // [157]
  "", // [158]
  "", // [159]
  "CIRCUMFLEX", // [160]
  "EXCLAMATION", // [161]
  "DOUBLE_QUOTE", // [162]
  "HASH", // [163]
  "DOLLAR", // [164]
  "PERCENT", // [165]
  "AMPERSAND", // [166]
  "UNDERSCORE", // [167]
  "OPEN_PAREN", // [168]
  "CLOSE_PAREN", // [169]
  "ASTERISK", // [170]
  "PLUS", // [171]
  "PIPE", // [172]
  "HYPHEN_MINUS", // [173]
  "OPEN_CURLY_BRACKET", // [174]
  "CLOSE_CURLY_BRACKET", // [175]
  "TILDE", // [176]
  "", // [177]
  "", // [178]
  "", // [179]
  "", // [180]
  "VOLUME_MUTE", // [181]
  "VOLUME_DOWN", // [182]
  "VOLUME_UP", // [183]
  "", // [184]
  "", // [185]
  "SEMICOLON", // [186]
  "EQUALS", // [187]
  "COMMA", // [188]
  "MINUS", // [189]
  "PERIOD", // [190]
  "SLASH", // [191]
  "BACK_QUOTE", // [192]
  "", // [193]
  "", // [194]
  "", // [195]
  "", // [196]
  "", // [197]
  "", // [198]
  "", // [199]
  "", // [200]
  "", // [201]
  "", // [202]
  "", // [203]
  "", // [204]
  "", // [205]
  "", // [206]
  "", // [207]
  "", // [208]
  "", // [209]
  "", // [210]
  "", // [211]
  "", // [212]
  "", // [213]
  "", // [214]
  "", // [215]
  "", // [216]
  "", // [217]
  "", // [218]
  "OPEN_BRACKET", // [219]
  "BACK_SLASH", // [220]
  "CLOSE_BRACKET", // [221]
  "QUOTE", // [222]
  "", // [223]
  "META", // [224]
  "ALTGR", // [225]
  "", // [226]
  "WIN_ICO_HELP", // [227]
  "WIN_ICO_00", // [228]
  "", // [229]
  "WIN_ICO_CLEAR", // [230]
  "", // [231]
  "", // [232]
  "WIN_OEM_RESET", // [233]
  "WIN_OEM_JUMP", // [234]
  "WIN_OEM_PA1", // [235]
  "WIN_OEM_PA2", // [236]
  "WIN_OEM_PA3", // [237]
  "WIN_OEM_WSCTRL", // [238]
  "WIN_OEM_CUSEL", // [239]
  "WIN_OEM_ATTN", // [240]
  "WIN_OEM_FINISH", // [241]
  "WIN_OEM_COPY", // [242]
  "WIN_OEM_AUTO", // [243]
  "WIN_OEM_ENLW", // [244]
  "WIN_OEM_BACKTAB", // [245]
  "ATTN", // [246]
  "CRSEL", // [247]
  "EXSEL", // [248]
  "EREOF", // [249]
  "PLAY", // [250]
  "ZOOM", // [251]
  "", // [252]
  "PA1", // [253]
  "WIN_OEM_CLEAR", // [254]
  "" // [255]
];

Note: The position of each value in the array above is important. The "" are placeholders for codes with unknown values.

Try the following code snippet using this static array lookup approach...

var keyCodes = [];

$("#reset").click(function() {
  keyCodes = [];
  $("#in").val("");
  $("#key-codes").html("var keyCodes = [ ];");
  $("#key-names").html("var keyNames = [ ];");
});

$(document).keydown(function(e) {
  keyCodes.push(e.which);
  updateOutput();
});

function updateOutput() {
  var kC = "var keyCodes = [ ";
  var kN = "var keyNames = [ ";

  var len = keyCodes.length;

  for (var i = 0; i < len; i++) {
    kC += keyCodes[i];
    kN += "'"+keyboardMap[keyCodes[i]]+"'";
    if (i !== (len - 1)) {
      kC += ", ";
      kN += ", ";
    }
  }

  kC += " ];";
  kN += " ];";

  $("#key-codes").html(kC);
  $("#key-names").html(kN);
}



var keyboardMap = [
  "", // [0]
  "", // [1]
  "", // [2]
  "CANCEL", // [3]
  "", // [4]
  "", // [5]
  "HELP", // [6]
  "", // [7]
  "BACK_SPACE", // [8]
  "TAB", // [9]
  "", // [10]
  "", // [11]
  "CLEAR", // [12]
  "ENTER", // [13]
  "ENTER_SPECIAL", // [14]
  "", // [15]
  "SHIFT", // [16]
  "CONTROL", // [17]
  "ALT", // [18]
  "PAUSE", // [19]
  "CAPS_LOCK", // [20]
  "KANA", // [21]
  "EISU", // [22]
  "JUNJA", // [23]
  "FINAL", // [24]
  "HANJA", // [25]
  "", // [26]
  "ESCAPE", // [27]
  "CONVERT", // [28]
  "NONCONVERT", // [29]
  "ACCEPT", // [30]
  "MODECHANGE", // [31]
  "SPACE", // [32]
  "PAGE_UP", // [33]
  "PAGE_DOWN", // [34]
  "END", // [35]
  "HOME", // [36]
  "LEFT", // [37]
  "UP", // [38]
  "RIGHT", // [39]
  "DOWN", // [40]
  "SELECT", // [41]
  "PRINT", // [42]
  "EXECUTE", // [43]
  "PRINTSCREEN", // [44]
  "INSERT", // [45]
  "DELETE", // [46]
  "", // [47]
  "0", // [48]
  "1", // [49]
  "2", // [50]
  "3", // [51]
  "4", // [52]
  "5", // [53]
  "6", // [54]
  "7", // [55]
  "8", // [56]
  "9", // [57]
  "COLON", // [58]
  "SEMICOLON", // [59]
  "LESS_THAN", // [60]
  "EQUALS", // [61]
  "GREATER_THAN", // [62]
  "QUESTION_MARK", // [63]
  "AT", // [64]
  "A", // [65]
  "B", // [66]
  "C", // [67]
  "D", // [68]
  "E", // [69]
  "F", // [70]
  "G", // [71]
  "H", // [72]
  "I", // [73]
  "J", // [74]
  "K", // [75]
  "L", // [76]
  "M", // [77]
  "N", // [78]
  "O", // [79]
  "P", // [80]
  "Q", // [81]
  "R", // [82]
  "S", // [83]
  "T", // [84]
  "U", // [85]
  "V", // [86]
  "W", // [87]
  "X", // [88]
  "Y", // [89]
  "Z", // [90]
  "OS_KEY", // [91] Windows Key (Windows) or Command Key (Mac)
  "", // [92]
  "CONTEXT_MENU", // [93]
  "", // [94]
  "SLEEP", // [95]
  "NUMPAD0", // [96]
  "NUMPAD1", // [97]
  "NUMPAD2", // [98]
  "NUMPAD3", // [99]
  "NUMPAD4", // [100]
  "NUMPAD5", // [101]
  "NUMPAD6", // [102]
  "NUMPAD7", // [103]
  "NUMPAD8", // [104]
  "NUMPAD9", // [105]
  "MULTIPLY", // [106]
  "ADD", // [107]
  "SEPARATOR", // [108]
  "SUBTRACT", // [109]
  "DECIMAL", // [110]
  "DIVIDE", // [111]
  "F1", // [112]
  "F2", // [113]
  "F3", // [114]
  "F4", // [115]
  "F5", // [116]
  "F6", // [117]
  "F7", // [118]
  "F8", // [119]
  "F9", // [120]
  "F10", // [121]
  "F11", // [122]
  "F12", // [123]
  "F13", // [124]
  "F14", // [125]
  "F15", // [126]
  "F16", // [127]
  "F17", // [128]
  "F18", // [129]
  "F19", // [130]
  "F20", // [131]
  "F21", // [132]
  "F22", // [133]
  "F23", // [134]
  "F24", // [135]
  "", // [136]
  "", // [137]
  "", // [138]
  "", // [139]
  "", // [140]
  "", // [141]
  "", // [142]
  "", // [143]
  "NUM_LOCK", // [144]
  "SCROLL_LOCK", // [145]
  "WIN_OEM_FJ_JISHO", // [146]
  "WIN_OEM_FJ_MASSHOU", // [147]
  "WIN_OEM_FJ_TOUROKU", // [148]
  "WIN_OEM_FJ_LOYA", // [149]
  "WIN_OEM_FJ_ROYA", // [150]
  "", // [151]
  "", // [152]
  "", // [153]
  "", // [154]
  "", // [155]
  "", // [156]
  "", // [157]
  "", // [158]
  "", // [159]
  "CIRCUMFLEX", // [160]
  "EXCLAMATION", // [161]
  "DOUBLE_QUOTE", // [162]
  "HASH", // [163]
  "DOLLAR", // [164]
  "PERCENT", // [165]
  "AMPERSAND", // [166]
  "UNDERSCORE", // [167]
  "OPEN_PAREN", // [168]
  "CLOSE_PAREN", // [169]
  "ASTERISK", // [170]
  "PLUS", // [171]
  "PIPE", // [172]
  "HYPHEN_MINUS", // [173]
  "OPEN_CURLY_BRACKET", // [174]
  "CLOSE_CURLY_BRACKET", // [175]
  "TILDE", // [176]
  "", // [177]
  "", // [178]
  "", // [179]
  "", // [180]
  "VOLUME_MUTE", // [181]
  "VOLUME_DOWN", // [182]
  "VOLUME_UP", // [183]
  "", // [184]
  "", // [185]
  "SEMICOLON", // [186]
  "EQUALS", // [187]
  "COMMA", // [188]
  "MINUS", // [189]
  "PERIOD", // [190]
  "SLASH", // [191]
  "BACK_QUOTE", // [192]
  "", // [193]
  "", // [194]
  "", // [195]
  "", // [196]
  "", // [197]
  "", // [198]
  "", // [199]
  "", // [200]
  "", // [201]
  "", // [202]
  "", // [203]
  "", // [204]
  "", // [205]
  "", // [206]
  "", // [207]
  "", // [208]
  "", // [209]
  "", // [210]
  "", // [211]
  "", // [212]
  "", // [213]
  "", // [214]
  "", // [215]
  "", // [216]
  "", // [217]
  "", // [218]
  "OPEN_BRACKET", // [219]
  "BACK_SLASH", // [220]
  "CLOSE_BRACKET", // [221]
  "QUOTE", // [222]
  "", // [223]
  "META", // [224]
  "ALTGR", // [225]
  "", // [226]
  "WIN_ICO_HELP", // [227]
  "WIN_ICO_00", // [228]
  "", // [229]
  "WIN_ICO_CLEAR", // [230]
  "", // [231]
  "", // [232]
  "WIN_OEM_RESET", // [233]
  "WIN_OEM_JUMP", // [234]
  "WIN_OEM_PA1", // [235]
  "WIN_OEM_PA2", // [236]
  "WIN_OEM_PA3", // [237]
  "WIN_OEM_WSCTRL", // [238]
  "WIN_OEM_CUSEL", // [239]
  "WIN_OEM_ATTN", // [240]
  "WIN_OEM_FINISH", // [241]
  "WIN_OEM_COPY", // [242]
  "WIN_OEM_AUTO", // [243]
  "WIN_OEM_ENLW", // [244]
  "WIN_OEM_BACKTAB", // [245]
  "ATTN", // [246]
  "CRSEL", // [247]
  "EXSEL", // [248]
  "EREOF", // [249]
  "PLAY", // [250]
  "ZOOM", // [251]
  "", // [252]
  "PA1", // [253]
  "WIN_OEM_CLEAR", // [254]
  "" // [255]
];
#key-codes,
#key-names {
  font-family: courier, serif;
  font-size: 1.2em;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input id="in" placeholder="Type here..." />
<button id="reset">Reset</button>
<br/>
<br/>
<div id="key-codes">var keyCodes = [ ];</div>
<div id="key-names">var keyNames = [ ];</div>

Key codes worth noting

Letters A-Z: (65-90)

keyboardMap[65];  // A
...
keyboardMap[90];  // Z

Digits 0-9: (48-57)

keyboardMap[48];  // 0
...
keyboardMap[57];  // 9

Number Pad 0-9: (96-105)

keyboardMap[96];   // NUMPAD0
...
keyboardMap[105];  // NUMPAD9

Arrow Keys: (37-40)

keyboardMap[37];  // LEFT
keyboardMap[38];  // UP
keyboardMap[39];  // RIGHT
keyboardMap[40];  // DOWN

Tab Key: (9)

keyboardMap[9];  // TAB

Enter Key: (13)

keyboardMap[13];  // ENTER

Spacebar Key: (32)

keyboardMap[32];  // SPACE

OS Specific Key (91) Windows Key (Windows) or Command Key (Mac)

keyboardMap[91];  // OS_KEY

Alt Key: (18)

keyboardMap[18];  // ALT

Control Key: (17)

keyboardMap[17];  // CONTROL

Shift Key: (16)

keyboardMap[16];  // SHIFT

Caps Lock Key: (20)

keyboardMap[20];  // CAPS_LOCK
DaveAlger
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19

Just an important note: the accepted answer above will not work correctly for keyCode >= 144, i.e. period, comma, dash, etc. For those you should use a more general algorithm:

let chrCode = keyCode - 48 * Math.floor(keyCode / 48);
let chr = String.fromCharCode((96 <= keyCode) ? chrCode: keyCode);

If you're curious as to why, this is apparently necessary because of the behavior of the built-in JS function String.fromCharCode(). For values of keyCode <= 96 it seems to map using the function:

chrCode = keyCode - 48 * Math.floor(keyCode / 48)

For values of keyCode > 96 it seems to map using the function:

chrCode = keyCode

If this seems like odd behavior then well..I agree. Sadly enough, it would be very far from the weirdest thing I've seen in the JS core.

document.onkeydown = function(e) {
    let keyCode = e.keyCode;
    let chrCode = keyCode - 48 * Math.floor(keyCode / 48);
    let chr = String.fromCharCode((96 <= keyCode) ? chrCode: keyCode);
    console.log(chr);
};
<input type="text" placeholder="Focus and Type"/>
KyleMit
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galarant
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2

I'm assuming this is for a game or for a fast-responding type of application hence the use of KEYDOWN than KEYPRESS.

Edit: Dang! I stand corrected (thank you Crescent Fresh and David): JQuery (or even rather the underlying DOM hosts) do not expose the detail of the WM_KEYDOWN and of other events. Rather they pre-digest this data and, in the case of keyDown even in JQuery, we get:

Note that these properties are the UniCode values.
Note, I wasn't able to find an authorititative reference to that in JQuery docs, but many reputable examples on the net refer to these two properties.

The following code, adapted from some java (not javascript) of mine, is therefore totally wrong...

The following will give you the "interesting" parts of the keycode:

  value = e.KeyCode;
  repeatCount = value & 0xFF;
  scanCode = (value >> 16) & 0xFF;  // note we take the "extended bit" deal w/ it later.
  wasDown = ((value & 0x4000) != 0);  // indicate key was readily down (auto-repeat)
  if (scanCode > 127)
      // deal with extended
  else
      // "regular" character
mjv
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  • hm, no go, scanCode always results in 0. And e.KeyCode should be e.keyCode (KeyCode is undefined). – David Murdoch Nov 20 '09 at 18:35
  • Hey now...Hello, wait...wha?? We talkin JScript here or something? – Crescent Fresh Nov 20 '09 at 18:36
  • @David M. My bad, maybe JQuery "pre-digests" these code parts for us. I'm looking into it now. – mjv Nov 20 '09 at 19:04
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    @mjv: where did you get this code? Has it ever worked for you? AFAIK no DOM implementation encodes all that info into the event object (`keydown` or not). – Crescent Fresh Nov 20 '09 at 19:08
  • @Crescent: I adapted it quickly and naively from some java code of mine, way old at that... Anyway, you are totally right: none of the DOM hosts hand-out any such raw events, even for the keyboard. I fixed my prose accordingly; still looking for an authoritative doc on the subject from JQuery.com – mjv Nov 20 '09 at 19:32
2

You can also use the read-only property key. It also respects special keys like shift etc. and is supported by IE9.

When a non-printable or special character is pressed, the value will be on of the defined key values like 'Shift' or 'Multiply'.

  • Keyboard     event.key
  • X             -> 'x'
  • Shift+X -> 'X'
  • F5            -> 'F5'
Kim Kern
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0

I know this is an old question, but I came across it today searching for a pre-packaged solution to this problem, and found nothing that really met my needs.

Here is a solution (English only) that correctly supports Upper Case (shifted), Lower Case, punctuation, number keypad, etc.

It also allows for simple and straight-forward identification of - and reaction to - non-printable keys, like ESC, Arrows, Function keys, etc.

https://jsfiddle.net/5hhu896g/1/

keyboardCharMap and keyboardNameMap are the key to making this work

Thanks to DaveAlger for saving me some typing - and much discovery! - by providing the Named Key Array.

halfer
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BRebey
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  • Your fiddle is most excellent! Thanks for sharing. It works excellently. I am using it to implement a Sublime-style multi-cursor edit for form fields with items having the same values – Todd Hammer Jun 23 '18 at 15:20
0

I recently wrote a module called keysight that translates keypress, keydown, and keyup events into characters and keys respectively.

Example:

 element.addEventListener("keydown", function(event) {
    var character = keysight(event).char
 })
B T
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  • does it supports keys like ñ? – Arnold Roa Sep 30 '16 at 17:05
  • @ArnoldRoa I just pushed something that hopefully will support characters like that. I don't have a keyboard with accented characters, so would you mind testing? – B T Oct 01 '16 at 01:46
0

For those of you who came here looking for the actual Unicode character values for a keycode, like I did, here is a function for that. For instance, given the right arrow unicode keycode this will output the visible string \u001B\u005B\u0043

function toUnicode(theString) {
    var unicodeString = '';
    for (var i = 0; i < theString.length; i++) {
        var theUnicode = theString.charCodeAt(i).toString(16).toUpperCase();
        while (theUnicode.length < 4) {
            theUnicode = '0' + theUnicode;
        }
        theUnicode = '\\u' + theUnicode;
        unicodeString += theUnicode;
    }
    return unicodeString;
}
-2

Refer this link Get Keycode from key press and char value for any key code

$('input#inp').keyup(function(e){
   $(this).val(String.fromCharCode(e.keyCode)); 
   $('div#output').html('Keycode : ' + e.keyCode);  
});