Remove duplicate characters from string

function nonRepeaters(s) {

  var h={};

  return s.split("").

    map(function(c){h[c] |= 0; h[c]++; console.log(c); return c}).

    filter(function(c){console.log(h[c]);return h[c] == 1}).

    join("");

 }



nonRepeaters("abcab")

output :

 a
 b
 c
 a
 b
 2
 2
 1
 2
 2

"c"