first_unique_char.js

//find first occurrence of a char in a given word
function first_unique_char(word)
{
 letter_obj = new Object();
 word_array =  word.split('');
  
  //first setup hash to store occurrences of char 
  for (var letter in  word_array){  
    if (letter_obj[word_array[letter]] === undefined){
      letter_obj[word_array[letter]] = 1;}
    else{
    letter_obj[word_array[letter]] = letter_obj[word_array[letter]] + 1;}  
  }
  
  //loop through second time and exit when char is 
  //unique (i.e., hash value == 1)
  for (var letter in word_array){
    if (letter_obj[word_array[letter]] == 1){
      return [word_array[letter]];}
  }
  
  
}


console.log(first_unique_char('google'));
console.log(first_unique_char('123454321'));