How can I know in Javascript if character is part of alphabet (not just English alphabet)?

Question

I need to analyze pressed key if it is alphabet (for all languages) in UTF-8 encoding. Is that possbile in anyway?

Answer 1

Using onkeypress it will look like this:

 document.onkeypress = function(e){
     var code = e.which || e.keyCode;
     // 65 - 90 for A-Z and 97 - 122 for a-z
     if((code >= 65 && code <= 90) || (code >= 97 && code <= 122)){
         // Some character between a and Z was pressed
     }
 }

Answer 2

Here we are going to use Java (which knows this stuff) to build a datafile of "alphabetic" characters. We Will use that datafile form JavaScript to get the desired behavior.

Step 1:
Use Java to build a text file containing "Letter" characters. Turns out to be 90K in size.

File f = new File("data.txt");

    OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(f), "Unicode");

    for (char c=0; c<Character.MAX_VALUE; c++){
      if (Character.isLetter(c)){
        writer.append(c);
      }
    }
    writer.flush();
    writer.close();
}

Step 2:
Use your favorite Ajax tool (jQuery, XMLHttpRequest) to pull in that file into your JavaScript and convert it into a string.

Step 3: Use String.fromCharCode(event.keyCode) in JavaScript to get the string, and search your big string for what you got. If it's there, it's a Letter. If it's not there, it's not a Letter.

Answer 3

With the XRegExp library and its Unicode plugin you can use this single call to test if a character is a Unicode letter:

XRegExp("^\\p{L}$").test(character)

Otherwise you can look all that Unicode letters up on your own.

---

Edit    Ok, here are the character ranges from the mentioned plugin’s source code in a character class:

[\u0041-\u005A\u0061-\u007A\u00AA\u00B5\u00BA\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u02C1\u02C6-\u02D1\u02E0-\u02E4\u02EC\u02EE\u0370-\u0374\u0376\u0377\u037A-\u037D\u0386\u0388-\u038A\u038C\u038E-\u03A1\u03A3-\u03F5\u03F7-\u0481\u048A-\u0523\u0531-\u0556\u0559\u0561-\u0587\u05D0-\u05EA\u05F0-\u05F2\u0621-\u064A\u066E\u066F\u0671-\u06D3\u06D5\u06E5\u06E6\u06EE\u06EF\u06FA-\u06FC\u06FF\u0710\u0712-\u072F\u074D-\u07A5\u07B1\u07CA-\u07EA\u07F4\u07F5\u07FA\u0904-\u0939\u093D\u0950\u0958-\u0961\u0971\u0972\u097B-\u097F\u0985-\u098C\u098F\u0990\u0993-\u09A8\u09AA-\u09B0\u09B2\u09B6-\u09B9\u09BD\u09CE\u09DC\u09DD\u09DF-\u09E1\u09F0\u09F1\u0A05-\u0A0A\u0A0F\u0A10\u0A13-\u0A28\u0A2A-\u0A30\u0A32\u0A33\u0A35\u0A36\u0A38\u0A39\u0A59-\u0A5C\u0A5E\u0A72-\u0A74\u0A85-\u0A8D\u0A8F-\u0A91\u0A93-\u0AA8\u0AAA-\u0AB0\u0AB2\u0AB3\u0AB5-\u0AB9\u0ABD\u0AD0\u0AE0\u0AE1\u0B05-\u0B0C\u0B0F\u0B10\u0B13-\u0B28\u0B2A-\u0B30\u0B32\u0B33\u0B35-\u0B39\u0B3D\u0B5C\u0B5D\u0B5F-\u0B61\u0B71\u0B83\u0B85-\u0B8A\u0B8E-\u0B90\u0B92-\u0B95\u0B99\u0B9A\u0B9C\u0B9E\u0B9F\u0BA3\u0BA4\u0BA8-\u0BAA\u0BAE-\u0BB9\u0BD0\u0C05-\u0C0C\u0C0E-\u0C10\u0C12-\u0C28\u0C2A-\u0C33\u0C35-\u0C39\u0C3D\u0C58\u0C59\u0C60\u0C61\u0C85-\u0C8C\u0C8E-\u0C90\u0C92-\u0CA8\u0CAA-\u0CB3\u0CB5-\u0CB9\u0CBD\u0CDE\u0CE0\u0CE1\u0D05-\u0D0C\u0D0E-\u0D10\u0D12-\u0D28\u0D2A-\u0D39\u0D3D\u0D60\u0D61\u0D7A-\u0D7F\u0D85-\u0D96\u0D9A-\u0DB1\u0DB3-\u0DBB\u0DBD\u0DC0-\u0DC6\u0E01-\u0E30\u0E32\u0E33\u0E40-\u0E46\u0E81\u0E82\u0E84\u0E87\u0E88\u0E8A\u0E8D\u0E94-\u0E97\u0E99-\u0E9F\u0EA1-\u0EA3\u0EA5\u0EA7\u0EAA\u0EAB\u0EAD-\u0EB0\u0EB2\u0EB3\u0EBD\u0EC0-\u0EC4\u0EC6\u0EDC\u0EDD\u0F00\u0F40-\u0F47\u0F49-\u0F6C\u0F88-\u0F8B\u1000-\u102A\u103F\u1050-\u1055\u105A-\u105D\u1061\u1065\u1066\u106E-\u1070\u1075-\u1081\u108E\u10A0-\u10C5\u10D0-\u10FA\u10FC\u1100-\u1159\u115F-\u11A2\u11A8-\u11F9\u1200-\u1248\u124A-\u124D\u1250-\u1256\u1258\u125A-\u125D\u1260-\u1288\u128A-\u128D\u1290-\u12B0\u12B2-\u12B5\u12B8-\u12BE\u12C0\u12C2-\u12C5\u12C8-\u12D6\u12D8-\u1310\u1312-\u1315\u1318-\u135A\u1380-\u138F\u13A0-\u13F4\u1401-\u166C\u166F-\u1676\u1681-\u169A\u16A0-\u16EA\u1700-\u170C\u170E-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176C\u176E-\u1770\u1780-\u17B3\u17D7\u17DC\u1820-\u1877\u1880-\u18A8\u18AA\u1900-\u191C\u1950-\u196D\u1970-\u1974\u1980-\u19A9\u19C1-\u19C7\u1A00-\u1A16\u1B05-\u1B33\u1B45-\u1B4B\u1B83-\u1BA0\u1BAE\u1BAF\u1C00-\u1C23\u1C4D-\u1C4F\u1C5A-\u1C7D\u1D00-\u1DBF\u1E00-\u1F15\u1F18-\u1F1D\u1F20-\u1F45\u1F48-\u1F4D\u1F50-\u1F57\u1F59\u1F5B\u1F5D\u1F5F-\u1F7D\u1F80-\u1FB4\u1FB6-\u1FBC\u1FBE\u1FC2-\u1FC4\u1FC6-\u1FCC\u1FD0-\u1FD3\u1FD6-\u1FDB\u1FE0-\u1FEC\u1FF2-\u1FF4\u1FF6-\u1FFC\u2071\u207F\u2090-\u2094\u2102\u2107\u210A-\u2113\u2115\u2119-\u211D\u2124\u2126\u2128\u212A-\u212D\u212F-\u2139\u213C-\u213F\u2145-\u2149\u214E\u2183\u2184\u2C00-\u2C2E\u2C30-\u2C5E\u2C60-\u2C6F\u2C71-\u2C7D\u2C80-\u2CE4\u2D00-\u2D25\u2D30-\u2D65\u2D6F\u2D80-\u2D96\u2DA0-\u2DA6\u2DA8-\u2DAE\u2DB0-\u2DB6\u2DB8-\u2DBE\u2DC0-\u2DC6\u2DC8-\u2DCE\u2DD0-\u2DD6\u2DD8-\u2DDE\u2E2F\u3005\u3006\u3031-\u3035\u303B\u303C\u3041-\u3096\u309D-\u309F\u30A1-\u30FA\u30FC-\u30FF\u3105-\u312D\u3131-\u318E\u31A0-\u31B7\u31F0-\u31FF\u3400\u4DB5\u4E00\u9FC3\uA000-\uA48C\uA500-\uA60C\uA610-\uA61F\uA62A\uA62B\uA640-\uA65F\uA662-\uA66E\uA67F-\uA697\uA717-\uA71F\uA722-\uA788\uA78B\uA78C\uA7FB-\uA801\uA803-\uA805\uA807-\uA80A\uA80C-\uA822\uA840-\uA873\uA882-\uA8B3\uA90A-\uA925\uA930-\uA946\uAA00-\uAA28\uAA40-\uAA42\uAA44-\uAA4B\uAC00\uD7A3\uF900-\uFA2D\uFA30-\uFA6A\uFA70-\uFAD9\uFB00-\uFB06\uFB13-\uFB17\uFB1D\uFB1F-\uFB28\uFB2A-\uFB36\uFB38-\uFB3C\uFB3E\uFB40\uFB41\uFB43\uFB44\uFB46-\uFBB1\uFBD3-\uFD3D\uFD50-\uFD8F\uFD92-\uFDC7\uFDF0-\uFDFB\uFE70-\uFE74\uFE76-\uFEFC\uFF21-\uFF3A\uFF41-\uFF5A\uFF66-\uFFBE\uFFC2-\uFFC7\uFFCA-\uFFCF\uFFD2-\uFFD7\uFFDA-\uFFDC]

Answer 4

Gumbo just gave the answer I had : Use the very nice XRegExp library with unicode plugin). However, since i already wrote it but couldn't add it as a comment, here's an example how to use the letter ranges (ripped off from the plugin code) in case you can't include it for some reason:

unicodeLetterRanges =     "[0041-005A0061-007A00AA00B500BA00C0-00D600D8-00F600F8-02C102C6-02D102E0-02E402EC02EE0370-037403760377037A-037D03860388-038A038C038E-03A103A3-03F503F7-0481048A-05230531-055605590561-058705D0-05EA05F0-05F20621-064A066E066F0671-06D306D506E506E606EE06EF06FA-06FC06FF07100712-072F074D-07A507B107CA-07EA07F407F507FA0904-0939093D09500958-096109710972097B-097F0985-098C098F09900993-09A809AA-09B009B209B6-09B909BD09CE09DC09DD09DF-09E109F009F10A05-0A0A0A0F0A100A13-0A280A2A-0A300A320A330A350A360A380A390A59-0A5C0A5E0A72-0A740A85-0A8D0A8F-0A910A93-0AA80AAA-0AB00AB20AB30AB5-0AB90ABD0AD00AE00AE10B05-0B0C0B0F0B100B13-0B280B2A-0B300B320B330B35-0B390B3D0B5C0B5D0B5F-0B610B710B830B85-0B8A0B8E-0B900B92-0B950B990B9A0B9C0B9E0B9F0BA30BA40BA8-0BAA0BAE-0BB90BD00C05-0C0C0C0E-0C100C12-0C280C2A-0C330C35-0C390C3D0C580C590C600C610C85-0C8C0C8E-0C900C92-0CA80CAA-0CB30CB5-0CB90CBD0CDE0CE00CE10D05-0D0C0D0E-0D100D12-0D280D2A-0D390D3D0D600D610D7A-0D7F0D85-0D960D9A-0DB10DB3-0DBB0DBD0DC0-0DC60E01-0E300E320E330E40-0E460E810E820E840E870E880E8A0E8D0E94-0E970E99-0E9F0EA1-0EA30EA50EA70EAA0EAB0EAD-0EB00EB20EB30EBD0EC0-0EC40EC60EDC0EDD0F000F40-0F470F49-0F6C0F88-0F8B1000-102A103F1050-1055105A-105D106110651066106E-10701075-1081108E10A0-10C510D0-10FA10FC1100-1159115F-11A211A8-11F91200-1248124A-124D1250-12561258125A-125D1260-1288128A-128D1290-12B012B2-12B512B8-12BE12C012C2-12C512C8-12D612D8-13101312-13151318-135A1380-138F13A0-13F41401-166C166F-16761681-169A16A0-16EA1700-170C170E-17111720-17311740-17511760-176C176E-17701780-17B317D717DC1820-18771880-18A818AA1900-191C1950-196D1970-19741980-19A919C1-19C71A00-1A161B05-1B331B45-1B4B1B83-1BA01BAE1BAF1C00-1C231C4D-1C4F1C5A-1C7D1D00-1DBF1E00-1F151F18-1F1D1F20-1F451F48-1F4D1F50-1F571F591F5B1F5D1F5F-1F7D1F80-1FB41FB6-1FBC1FBE1FC2-1FC41FC6-1FCC1FD0-1FD31FD6-1FDB1FE0-1FEC1FF2-1FF41FF6-1FFC2071207F2090-209421022107210A-211321152119-211D212421262128212A-212D212F-2139213C-213F2145-2149214E218321842C00-2C2E2C30-2C5E2C60-2C6F2C71-2C7D2C80-2CE42D00-2D252D30-2D652D6F2D80-2D962DA0-2DA62DA8-2DAE2DB0-2DB62DB8-2DBE2DC0-2DC62DC8-2DCE2DD0-2DD62DD8-2DDE2E2F300530063031-3035303B303C3041-3096309D-309F30A1-30FA30FC-30FF3105-312D3131-318E31A0-31B731F0-31FF34004DB54E009FC3A000-A48CA500-A60CA610-A61FA62AA62BA640-A65FA662-A66EA67F-A697A717-A71FA722-A788A78BA78CA7FB-A801A803-A805A807-A80AA80C-A822A840-A873A882-A8B3A90A-A925A930-A946AA00-AA28AA40-AA42AA44-AA4BAC00D7A3F900-FA2DFA30-FA6AFA70-FAD9FB00-FB06FB13-FB17FB1DFB1F-FB28FB2A-FB36FB38-FB3CFB3EFB40FB41FB43FB44FB46-FBB1FBD3-FD3DFD50-FD8FFD92-FDC7FDF0-FDFBFE70-FE74FE76-FEFCFF21-FF3AFF41-FF5AFF66-FFBEFFC2-FFC7FFCA-FFCFFFD2-FFD7FFDA-FFDC]";

    unicodeLetterRanges =  unicodeLetterRanges.replace(/\w{4}/g, "\\u$&");
    reUnicodeLetterRanges = new RegExp(unicodeLetterRanges);
    reUnicodeLetterRanges.test("a5");

    function isUnicodeLetters(str) {
        return reUnicodeLetterRanges.test(str);
    }

    //usage
    isUnicodeLetters("123"); //false
    isUnicodeLetters("בלה"); //true

Then just use it on the character string you got from the keypress event as answered.