How to approximate Java's Character.isLetterOrDigit() to identify non-English letters, digits in Javascript?

Question

In Javascript, is there a way (that survives internationalization) to determine whether a character is a letter or digit? That will correctly identify Ä, ç as letters, and non-English digits (which I am not going to look up as examples)!

In Java, the Character class has some static methods .isLetter(), .isDigit(), .isLetterOrDigit(), for determining in an internationally suitable way that a char is actually a letter or digit. This is better than code like

//this is not right, but common and easy
if((ch>='A'&&ch<='Z')||(ch>='a'&&ch<='z')) { //it's a letter

because it will pick up non-English letters. I think C# has similar capabilities...

Of course, at worst I can send strings back to the server to be checked but that's a pain...

Of course, in the end I am looking to check if input is a valid name (starts with a letter, the rest is letter or digit). An outside the box possibility for low volume use might be:

var validName=function(atr) {
    var ele=document.createElement("div");
    try { ele.setAttribute(atr,"xxx"); }
    catch(e) { return false; }
    return true;
    }

This tests out fairly decent in IE, FF and Chrome... Though thorough testing might be needed to figure out how consistent the answers are. And again, not appropriate for heavy duty usage due to element creation.

Answer 1

As far as I could tell when faced with a similar problem, the only way was really picking a couple of blocks and assume those are letters. The unicode standard has the full lists, so you could build a complete regex for this (I think). For instance, if you take all characters that are "alphabetic" according to this list you probably have all alphabetic characters. Likewise for numeric (decimal, digit, numeric) in the main unicode data file.

I'm not entirely sure if I'm pointing in the correct direction. There's a bunch of Unicode code charts that might help, and there's of course the unicode standard itself. It's all a bit much to read and understand though, especially if your only goal is to do some javascript string verification.

Answer 2

I have created a small Javascript utility to provide this functionality. I don't claim it is perfect, so let me know how you fair. If people like it, I'll make this the official answer to this question.

CharFunk: http://code.google.com/p/charfunk/

var CharFunk={
  GTYPE_LETTER: 1,
  GTYPE_DIGIT: 2,
  GTYPE_OTHER: 3,
  NAME_ALLOW_STANDARD:"_-",
  GTYPE_TABLE:{0:3,48:2,58:3,65:1,91:3,97:1,123:3,170:1,171:3,181:1,182:3,186:1,187:3,192:1,215:3,216:1,247:3,248:1,567:3,592:1,706:3,710:1,722:3,736:1,741:3,750:1,751:3,890:1,891:3,902:1,903:3,904:1,907:3,908:1,909:3,910:1,930:3,931:1,975:3,976:1,1014:3,1015:1,1020:3,1024:1,1154:3,1162:1,1231:3,1232:1,1270:3,1272:1,1274:3,1280:1,1296:3,1329:1,1367:3,1369:1,1370:3,1377:1,1416:3,1488:1,1515:3,1520:1,1523:3,1569:1,1595:3,1600:1,1611:3,1632:2,1642:3,1646:1,1648:3,1649:1,1748:3,1749:1,1750:3,1765:1,1767:3,1774:1,1776:2,1786:1,1789:3,1791:1,1792:3,1808:1,1809:3,1810:1,1840:3,1869:1,1872:3,1920:1,1958:3,1969:1,1970:3,2308:1,2362:3,2365:1,2366:3,2384:1,2385:3,2392:1,2402:3,2406:2,2416:3,2437:1,2445:3,2447:1,2449:3,2451:1,2473:3,2474:1,2481:3,2482:1,2483:3,2486:1,2490:3,2493:1,2494:3,2524:1,2526:3,2527:1,2530:3,2534:2,2544:1,2546:3,2565:1,2571:3,2575:1,2577:3,2579:1,2601:3,2602:1,2609:3,2610:1,2612:3,2613:1,2615:3,2616:1,2618:3,2649:1,2653:3,2654:1,2655:3,2662:2,2672:3,2674:1,2677:3,2693:1,2702:3,2703:1,2706:3,2707:1,2729:3,2730:1,2737:3,2738:1,2740:3,2741:1,2746:3,2749:1,2750:3,2768:1,2769:3,2784:1,2786:3,2790:2,2800:3,2821:1,2829:3,2831:1,2833:3,2835:1,2857:3,2858:1,2865:3,2866:1,2868:3,2869:1,2874:3,2877:1,2878:3,2908:1,2910:3,2911:1,2914:3,2918:2,2928:3,2929:1,2930:3,2947:1,2948:3,2949:1,2955:3,2958:1,2961:3,2962:1,2966:3,2969:1,2971:3,2972:1,2973:3,2974:1,2976:3,2979:1,2981:3,2984:1,2987:3,2990:1,2998:3,2999:1,3002:3,3047:2,3056:3,3077:1,3085:3,3086:1,3089:3,3090:1,3113:3,3114:1,3124:3,3125:1,3130:3,3168:1,3170:3,3174:2,3184:3,3205:1,3213:3,3214:1,3217:3,3218:1,3241:3,3242:1,3252:3,3253:1,3258:3,3261:1,3262:3,3294:1,3295:3,3296:1,3298:3,3302:2,3312:3,3333:1,3341:3,3342:1,3345:3,3346:1,3369:3,3370:1,3386:3,3424:1,3426:3,3430:2,3440:3,3461:1,3479:3,3482:1,3506:3,3507:1,3516:3,3517:1,3518:3,3520:1,3527:3,3585:1,3633:3,3634:1,3636:3,3648:1,3655:3,3664:2,3674:3,3713:1,3715:3,3716:1,3717:3,3719:1,3721:3,3722:1,3723:3,3725:1,3726:3,3732:1,3736:3,3737:1,3744:3,3745:1,3748:3,3749:1,3750:3,3751:1,3752:3,3754:1,3756:3,3757:1,3761:3,3762:1,3764:3,3773:1,3774:3,3776:1,3781:3,3782:1,3783:3,3792:2,3802:3,3804:1,3806:3,3840:1,3841:3,3872:2,3882:3,3904:1,3912:3,3913:1,3947:3,3976:1,3980:3,4096:1,4130:3,4131:1,4136:3,4137:1,4139:3,4160:2,4170:3,4176:1,4182:3,4256:1,4294:3,4304:1,4345:3,4352:1,4442:3,4447:1,4515:3,4520:1,4602:3,4608:1,4615:3,4616:1,4679:3,4680:1,4681:3,4682:1,4686:3,4688:1,4695:3,4696:1,4697:3,4698:1,4702:3,4704:1,4743:3,4744:1,4745:3,4746:1,4750:3,4752:1,4783:3,4784:1,4785:3,4786:1,4790:3,4792:1,4799:3,4800:1,4801:3,4802:1,4806:3,4808:1,4815:3,4816:1,4823:3,4824:1,4847:3,4848:1,4879:3,4880:1,4881:3,4882:1,4886:3,4888:1,4895:3,4896:1,4935:3,4936:1,4955:3,4969:2,4978:3,5024:1,5109:3,5121:1,5521:1,5741:3,5743:1,5751:3,5761:1,5787:3,5792:1,5867:3,5888:1,5901:3,5902:1,5906:3,5920:1,5938:3,5952:1,5970:3,5984:1,5997:3,5998:1,6001:3,6016:1,6068:3,6103:1,6104:3,6108:1,6109:3,6112:2,6122:3,6160:2,6170:3,6176:1,6264:3,6272:1,6313:3,6400:1,6429:3,6470:2,6480:1,6510:3,6512:1,6517:3,6917:3,7317:3,7424:1,7532:3,7680:1,7836:3,7840:1,7930:3,7936:1,7958:3,7960:1,7966:3,7968:1,8006:3,8008:1,8014:3,8016:1,8024:3,8025:1,8026:3,8027:1,8028:3,8029:1,8030:3,8031:1,8062:3,8064:1,8117:3,8118:1,8125:3,8126:1,8127:3,8130:1,8133:3,8134:1,8141:3,8144:1,8148:3,8150:1,8156:3,8160:1,8173:3,8178:1,8181:3,8182:1,8189:3,8305:1,8306:3,8319:1,8320:3,8450:1,8451:3,8455:1,8456:3,8458:1,8468:3,8469:1,8470:3,8473:1,8478:3,8484:1,8485:3,8486:1,8487:3,8488:1,8489:3,8490:1,8494:3,8495:1,8498:3,8499:1,8506:3,8509:1,8512:3,8517:1,8522:3,8922:3,9322:3,9722:3,10122:3,10522:3,10922:3,11322:3,11722:3,12122:3,12293:1,12295:3,12337:1,12342:3,12347:1,12349:3,12353:1,12439:3,12445:1,12448:3,12449:1,12539:3,12540:1,12544:3,12549:1,12589:3,12593:1,12687:3,12704:1,12728:3,12784:1,12800:3,13200:3,13312:1,13712:1,14112:1,14512:1,14912:1,15312:1,15712:1,16112:1,16512:1,16912:1,17312:1,17712:1,18112:1,18512:1,18912:1,19312:1,19712:1,19894:3,19968:1,20368:1,20768:1,21168:1,21568:1,21968:1,22368:1,22768:1,23168:1,23568:1,23968:1,24368:1,24768:1,25168:1,25568:1,25968:1,26368:1,26768:1,27168:1,27568:1,27968:1,28368:1,28768:1,29168:1,29568:1,29968:1,30368:1,30768:1,31168:1,31568:1,31968:1,32368:1,32768:1,33168:1,33568:1,33968:1,34368:1,34768:1,35168:1,35568:1,35968:1,36368:1,36768:1,37168:1,37568:1,37968:1,38368:1,38768:1,39168:1,39568:1,39968:1,40368:1,40768:1,40870:3,40960:1,41360:1,41760:1,42125:3,42525:3,42925:3,43325:3,43725:3,44032:1,44432:1,44832:1,45232:1,45632:1,46032:1,46432:1,46832:1,47232:1,47632:1,48032:1,48432:1,48832:1,49232:1,49632:1,50032:1,50432:1,50832:1,51232:1,51632:1,52032:1,52432:1,52832:1,53232:1,53632:1,54032:1,54432:1,54832:1,55204:3,55604:3,56004:3,56404:3,56804:3,57204:3,57604:3,58004:3,58404:3,58804:3,59204:3,59604:3,60004:3,60404:3,60804:3,61204:3,61604:3,62004:3,62404:3,62804:3,63204:3,63604:3,63744:1,64046:3,64048:1,64107:3,64256:1,64263:3,64275:1,64280:3,64285:1,64286:3,64287:1,64297:3,64298:1,64311:3,64312:1,64317:3,64318:1,64319:3,64320:1,64322:3,64323:1,64325:3,64326:1,64434:3,64467:1,64830:3,64848:1,64912:3,64914:1,64968:3,65008:1,65020:3,65136:1,65141:3,65142:1,65277:3,65296:2,65306:3,65313:1,65339:3,65345:1,65371:3,65382:1,65471:3,65474:1,65480:3,65482:1,65488:3,65490:1,65496:3,65498:1,65501:0},
  WSPACE_TABLE:{9:1,10:1,11:1,12:1,13:1,28:1,29:1,30:1,31:1,32:1,5760:1,6158:1,8192:1,8193:1,8194:1,8195:1,8196:1,8197:1,8198:1,8200:1,8201:1,8202:1,8203:1,8232:1,8233:1,8287:1,12288:1},
  getGeneralType:function(cp) {
    if(typeof cp=="string") { cp=cp.charCodeAt(0); }
    if(cp<0 || cp>65535) { return this.GTYPE_OTHER; }
    while(!this.GTYPE_TABLE[cp] && cp>0) { cp--; }
    return this.GTYPE_TABLE[cp];
    },
  isLetterOrDigit:function(ch) {
    return (this.getGeneralType(ch)!=this.GTYPE_OTHER);
    },
  isDigit:function(ch) {
    return (this.getGeneralType(ch)==this.GTYPE_DIGIT);
    },
  isLetter:function(ch) {
    return (this.getGeneralType(ch)==this.GTYPE_LETTER);
    },
  isWhiteSpace:function(ch) {
    return (this.WSPACE_TABLE[ch.charCodeAt(0)]==1);
    },
  allLettersOrDigits:function(str,frm) {
    for(var ci=frm || 0; ci<str.length; ci++) {
      if(!this.isLetterOrDigit(str.charAt(ci))) { return false; }
      }
    return true;
    },
  isValidFirst:function(str) {
    return (this.isLetter(str.charAt(0)) || str.charAt(0)=='_');
    },
  isValidName:function(str,alw) {
    if(!this.isValidFirst(str)) { return false; }
    alw=alw || this.NAME_ALLOW_STANDARD;
    for(var ci=1; ci<str.length; ci++) {
      if(!this.isLetterOrDigit(str.charAt(ci)) && alw.indexOf(str.charAt(ci))) { return false; }
      }
    return true;
    }
};