//找出字符串中第一个不重复的字符  // firstUniqueChar("vdctdvc"); --> t  function firstUniqueChar(str){    var str = str || "",        i = 0,        k = "",        _char = "",        charMap = {},        result = {name: "",index: str.length};    for(i=0;i<str.length;i++){      _char = str.charAt(i);      if(charMap[_char] != undefined){        charMap[_char] = -1;      }else{        charMap[_char] = i;      }    }    for(k in charMap){      if(charMap[k]<0){        continue;      }      if(result.index>charMap[k]){        result.index = charMap[k];        result.name = k;      }    }    return result.name;  }