persian character converter react

convert() {
    var numerals = {
      persian : ["۰", "۱", "۲", "۳", "۴", "۵", "۶", "۷", "۸", "۹"],
      arabic  : ["٠", "١", "٢", "٣", "٤", "٥", "٦", "٧", "٨", "٩"]
    };

    function fromEnglish(str, lang){
      var i, len = str.length, result = "";

      for( i = 0; i < len; i++ )
          result += numerals[lang][str[i]]; 

      return result;
    }

    return {
      toNormal : function(str){
          var num, i, len = str.length, result = "";

          for( i = 0; i < len; i++ ){
              num = numerals["persian"].indexOf(str[i]);
              num = num != -1 ? num : numerals["arabic"].indexOf(str[i]);
              if( num == -1 ) num = str[i];
              result += num; 
          }
            
          return result;
      },

      toPersian : function(str, lang){
          return fromEnglish(str, "persian");
      },

      toArabic : function(str){
          return fromEnglish(str, "arabic");
      }
    }
  }

call it like this.convert().toNormal(12312312۱۲۳۱۲۳۱۲۳2314123۲۳۴۲۳۴)