tohen

<script>
var str ="adadfdfseffserfefsefseeffffftsdg";
var maxLength = 0
var result = ''

while( str != '' )
{
      oldStr = str
      getStr = str.substr(0,1)
      eval("str = str.replace(/"+getStr+"/g,'')")

      if( oldStr.length-str.length > maxLength )
      {
            maxLength =  oldStr.length-str.length
            result = getStr + "=" + maxLength
      }
}
      alert(result)

</script>