transliterating cyrillic to latin with javascript function

Question

I made this function:

function transliterate(word){

    var answer = "";

    A = new Array();
    A["Ё"]="YO";A["Й"]="I";A["Ц"]="TS";A["У"]="U";A["К"]="K";A["Е"]="E";A["Н"]="N";A["Г"]="G";A["Ш"]="SH";A["Щ"]="SCH";A["З"]="Z";A["Х"]="H";A["Ъ"]="'";
    A["ё"]="yo";A["й"]="i";A["ц"]="ts";A["у"]="u";A["к"]="k";A["е"]="e";A["н"]="n";A["г"]="g";A["ш"]="sh";A["щ"]="sch";A["з"]="z";A["х"]="h";A["ъ"]="'";
    A["Ф"]="F";A["Ы"]="I";A["В"]="V";A["А"]="A";A["П"]="P";A["Р"]="R";A["О"]="O";A["Л"]="L";A["Д"]="D";A["Ж"]="ZH";A["Э"]="E";
    A["ф"]="f";A["ы"]="i";A["в"]="v";A["а"]="a";A["п"]="p";A["р"]="r";A["о"]="o";A["л"]="l";A["д"]="d";A["ж"]="zh";A["э"]="e";
    A["Я"]="YA";A["Ч"]="CH";A["С"]="S";A["М"]="M";A["И"]="I";A["Т"]="T";A["Ь"]="'";A["Б"]="B";A["Ю"]="YU";
    A["я"]="ya";A["ч"]="ch";A["с"]="s";A["м"]="m";A["и"]="i";A["т"]="t";A["ь"]="'";A["б"]="b";A["ю"]="yu";

for (i in word){

    if (A[word[i]] === 'undefined'){
        answer += word[i];
        }
    else {
        answer += A[word[i]];
        }

return answer;
}
}

Now it should transliterate cyrillic text to latin and let latin simply pass. But it only manages to transliterate the first later and in case of latin it gives undefined as an answer. Could anyone give me an idea, what am i doing wrong?

Answer 1

Couple of things...

1. Use undefined instead of 'undefined'
2. Don't put the return in the loop
3. Use hasOwnProperty to filter out functions and properties on the prototype
4. Use [] instead of new Array()
5. Use an {} instead of an []
6. Use lower case variables instead of upper case. Uppercase is reserved for constructors

Here is the code

function transliterate(word){
    var answer = ""
      , a = {};

   a["Ё"]="YO";a["Й"]="I";a["Ц"]="TS";a["У"]="U";a["К"]="K";a["Е"]="E";a["Н"]="N";a["Г"]="G";a["Ш"]="SH";a["Щ"]="SCH";a["З"]="Z";a["Х"]="H";a["Ъ"]="'";
   a["ё"]="yo";a["й"]="i";a["ц"]="ts";a["у"]="u";a["к"]="k";a["е"]="e";a["н"]="n";a["г"]="g";a["ш"]="sh";a["щ"]="sch";a["з"]="z";a["х"]="h";a["ъ"]="'";
   a["Ф"]="F";a["Ы"]="I";a["В"]="V";a["А"]="a";a["П"]="P";a["Р"]="R";a["О"]="O";a["Л"]="L";a["Д"]="D";a["Ж"]="ZH";a["Э"]="E";
   a["ф"]="f";a["ы"]="i";a["в"]="v";a["а"]="a";a["п"]="p";a["р"]="r";a["о"]="o";a["л"]="l";a["д"]="d";a["ж"]="zh";a["э"]="e";
   a["Я"]="Ya";a["Ч"]="CH";a["С"]="S";a["М"]="M";a["И"]="I";a["Т"]="T";a["Ь"]="'";a["Б"]="B";a["Ю"]="YU";
   a["я"]="ya";a["ч"]="ch";a["с"]="s";a["м"]="m";a["и"]="i";a["т"]="t";a["ь"]="'";a["б"]="b";a["ю"]="yu";

   for (i in word){
     if (word.hasOwnProperty(i)) {
       if (a[word[i]] === undefined){
         answer += word[i];
       } else {
         answer += a[word[i]];
       }
     }
   }
   return answer;
}

More functional one is like this...

var a = {"Ё":"YO","Й":"I","Ц":"TS","У":"U","К":"K","Е":"E","Н":"N","Г":"G","Ш":"SH","Щ":"SCH","З":"Z","Х":"H","Ъ":"'","ё":"yo","й":"i","ц":"ts","у":"u","к":"k","е":"e","н":"n","г":"g","ш":"sh","щ":"sch","з":"z","х":"h","ъ":"'","Ф":"F","Ы":"I","В":"V","А":"a","П":"P","Р":"R","О":"O","Л":"L","Д":"D","Ж":"ZH","Э":"E","ф":"f","ы":"i","в":"v","а":"a","п":"p","р":"r","о":"o","л":"l","д":"d","ж":"zh","э":"e","Я":"Ya","Ч":"CH","С":"S","М":"M","И":"I","Т":"T","Ь":"'","Б":"B","Ю":"YU","я":"ya","ч":"ch","с":"s","м":"m","и":"i","т":"t","ь":"'","б":"b","ю":"yu"};

function transliterate(word){
  return word.split('').map(function (char) { 
    return a[char] || char; 
  }).join("");
}