js查找字符不重复字符源码实例

<script>
function firstUniqueChar(str){
  var str=str||"",
      index = 0,
      k = "",
      _char = "",
      charMap = {},
      result={name: "",index: str.length};
  
  for(index=0;index<str.length;index++){
    _char = str.charAt(index);
    if(charMap[_char] != undefined){
      charMap[_char] = -1;
    }
    else{
      charMap[_char] = index;
    }
  }
  
  for(k in charMap){
    if(charMap[k]<0){
      continue;
    }
    if(result.index>charMap[k]){
      result.index = charMap[k];
      result.name = k;
    }
  }
  return result.name;
}
var str="antzone";
console.log(firstUniqueChar(str));
</script>