BASH filter list while typing

#!/bin/bash
#Copyright Kris Occhipinti 2018
#http://filmsbykris.com
#license GPLv3 - https://www.gnu.org/licenses/gpl.txt

l=$(ls *.jpg)
tmp_i=""
i=""
viewer="feh"

clear
echo "$l"

function prompt(){
  clear
  output="$(echo "$l"|grep -i "$i")"
  count="$(echo "$l"|grep -i "$i"|wc -l)"

  echo "$count results for $i"
  echo "===================================="
  echo "$output"

}

while true; do
read -rsn1 input
  i+=$input
  prompt

  if [ "$output" == "" ]
  then
    echo "No Entries Found for ${i}..."
    echo "Clearing list"
    i="$tmp_i";
    sleep 1
    prompt
  elif [ $count -eq 1 ]
  then
    clear
    echo "$output is found"
    $viewer "$output"
    i=""
    prompt
    #break
  fi
  tmp_i="$i"

done