Question

I have a javascript case conversion problem which I cannot solve due to non-English letters. My main concern is the Turkish alphabet.

What I need to do is this:

• hello world => Hello World
• HELLO WORLD => Hello World
• hELLO wOrLd => Hello World

Here is what I’ve accomplished so far:

String.prototype.turkishToUpper = function(){
    var stringlow = this;
    var letterslow = { 'i': 'İ', 'ş': 'Ş', 'ğ': 'Ğ', 'ü': 'Ü', 'ö': 'Ö', 'ç': 'Ç', 'ı': 'I' };
    stringlow = stringlow.replace(/(([iışğüçö]))/g, function(letterlow){ return letterslow[letterlow]; })
    return stringlow.toUpperCase();
}

String.prototype.turkishToLower = function(){
    var stringup = this;
    var lettersup = { 'İ': 'i', 'I': 'ı', 'Ş': 'ş', 'Ğ': 'ğ', 'Ü': 'ü', 'Ö': 'ö', 'Ç': 'ç' };
    stringup = stringup.replace(/(([İIŞĞÜÇÖ]))/g, function(letterup){ return lettersup[letterup]; })
    return stringup.toLowerCase();
}

String.prototype.toProperCase = function () {
    return this.replace(/\w\S*/g, function(txt){return txt.charAt(0).turkishToUpper() + txt.substr(1).turkishToLower();});
};

But this does not give me the correct results and I am suspecting the regex replace not being usable on unicode, but ascii.

When I test with Turkish characters, I get wrong results.

• şeker becomes şEker instead of Şeker
• çoban ırmak becomes çOban ıRmak intead of Çoban Irmak

Also, if this can ever get resolved, I need an icing on the cake to separate words not only by spaces, but also by some other stop characters such as : – = / etc so that

• hello-world becomes Hello-World
• hello:world becomes Hello:World

I’ve read through many similar questions here on SO, but no luck so far.

Thanks

Note: I think this is called Title Case but some have argued that it is Pascal Case. To be frank, I am interested in resolving the unicode issue (which I believe is the root cause) rather than semantics, so please forgive me if I’ve used wrong terminology 🙂

Answer 1

Standalone function:

function toProperCase(s){
    return s.replace(/([^\s:\-])([^\s:\-]*)/g,function($0,$1,$2){
        return $1.toUpperCase()+$2.toLowerCase();
    });
}

Or for extending of String.prototype:

String.prototype.toProperCase=function() {
    return this.replace(/([^\s:\-])([^\s:\-]*)/g,function($0,$1,$2){
        return $1.toUpperCase()+$2.toLowerCase();
    });
}

"çoban ırmak becomes çOban ıRmak intead of Çoban Irmak Hello-wOrld".toProperCase();
// "Çoban Irmak Becomes Çoban Irmak Intead Of Çoban Irmak Hello-World"

Update:

Next code uses custom functionality for converting locale specific chars (tested partially). Code adds functions into String.prototype: toLocaleProperCase2, toLocaleLowerCase2 and toLocaleUpperCase2.

(function(){
    // locale specific chars
    // IMPORTANT: name of locale must be always in lower case (for "tr-TR" locale - "tr-tr") !!!
    var localeInfos={
            "tr-tr": { lower: { i:"İ", ı:"I", ş:"Ş", ğ:"Ğ", ü:"Ü", ç:"Ç", ö:"Ö" },
                       upper: { İ:"i", I:"ı", Ş:"ş", Ğ:"ğ", Ü:"ü", Ç:"ç", Ö:"ö" } }
        },
        localeInfo;
    // helper vars
    var mask="\\s:\\-", // add additional delimeters chars to the mask if needed
        rg=new RegExp("([^"+mask+"])([^"+mask+"]*)","g");
    var fnToLocaleLower=function(s){ return localeInfo.upper[s]; },
        fnToLocaleUpper=function(s){ return localeInfo.lower[s]; },
        fnToProper=function($0,$1,$2){
            if(localeInfo){
                if(localeInfo.lower.hasOwnProperty($1))$1=localeInfo.lower[$1];
                $2=$2.replace(localeInfo.upperSearchRegExp,fnToLocaleLower);
            }
            return $1.toUpperCase()+$2.toLowerCase();
        };
    // helper calculations
    var localeInfosKeys=Object.keys(localeInfos);
    for(var i=0;localeInfo=localeInfos[localeInfosKeys[i]];i++){
        localeInfo.lowerSearchRegExp=new RegExp("["+Object.keys(localeInfo.lower).join("")+"]","g");
        localeInfo.upperSearchRegExp=new RegExp("["+Object.keys(localeInfo.upper).join("")+"]","g");
    }

    // extending String.prototype
    String.prototype.toLocaleProperCase2=function toLocaleProperCase2(locale){
        localeInfo=localeInfos[arguments.length?locale.toLowerCase():null];
        return this.replace(rg,fnToProper);
    };
    String.prototype.toLocaleLowerCase2=function toLocaleLowerCase2(locale){
        return ((localeInfo=localeInfos[arguments.length?locale.toLowerCase():null]) ?
                this.replace(localeInfo.upperSearchRegExp,fnToLocaleLower):
                this).toLowerCase();
    };
    String.prototype.toLocaleUpperCase2=function toLocaleUpperCase2(locale){
        return ((localeInfo=localeInfos[arguments.length?locale.toLowerCase():null]) ?
                this.replace(localeInfo.lowerSearchRegExp,fnToLocaleUpper) :
                this).toUpperCase();
    };
})();

---

// testing
var sss="çoban ırmak ibecıoimes çOban ıRmak intead of Çoban IrImaİk Hello-wOrld";
console.log("Origin:    ", sss);
console.log("Proper TR: ", sss.toLocaleProperCase2("tr-TR"));
console.log("Proper:    ", sss.toLocaleProperCase2());
console.log("Lower TR:  ", sss.toLocaleLowerCase2("tr-TR"));
console.log("Lower:     ", sss.toLocaleLowerCase2());
console.log("Upper TR:  ", sss.toLocaleUpperCase2("tr-TR"));
console.log("Upper:     ", sss.toLocaleUpperCase2());

// Origin:    çoban ırmak ibecıoimes çOban ıRmak intead of Çoban IrImaİk Hello-wOrld
// Proper TR: Çoban Irmak İbecıoimes Çoban Irmak İntead Of Çoban Irımaik Hello-World
// Proper:    Çoban Irmak Ibecıoimes Çoban Irmak Intead Of Çoban Irimaik Hello-World
// Lower TR:  çoban ırmak ibecıoimes çoban ırmak intead of çoban ırımaik hello-world
// Lower:     çoban ırmak ibecıoimes çoban ırmak intead of çoban irimaik hello-world
// Upper TR:  ÇOBAN IRMAK İBECIOİMES ÇOBAN IRMAK İNTEAD OF ÇOBAN IRIMAİK HELLO-WORLD
// Upper:     ÇOBAN IRMAK IBECIOIMES ÇOBAN IRMAK INTEAD OF ÇOBAN IRIMAİK HELLO-WORLD