Edited it a bit make it more stylish

ON *:JOIN:#: { 
  if (%whoison [ $+ [ $chan ] ] != $null) {
    set %thisuser $nick
    set %chan2whois $chan 
    whois $nick 
  } 
}
raw 319:*:{  
  msg %chan2whois 11[15Channel Checker11] 11[15 $+ %thisuser Is On11] 11[15  $3- 11]
  unset %chan2whois 
} 

on *:text:.wON:#:{
  if ($nick isop $chan) || ($nick ishop $chan) {
    if (%whoison [ $+ [ $chan ] ] == $null) {
      set %whoison [ $+ [ $chan ] ] sup
      set %whoischecker [ $+ [ $chan ] ] on
      msg $chan 11[15Chan Checker Is Now On.11]
    }
    else notice $nick 11[15It\'s Already On11]
  }
  else notice $nick 11[15You Need To Be Op or Hop To Use Chan Checker.11]
}

on *:text:.wOFF:#:{
  if ($nick isop $chan) || ($nick ishop $chan) {
    if (%whoison [ $+ [ $chan ] ] != $null) {
      unset %whoison [ $+ [ $chan ] ]
      set %whoischecker [ $+ [ $chan ] ] off
      msg $chan 11[15Chan Checker Is Now Off.11]
    }
    else notice $nick 11[15It\'s Already Off11]
  }
  else notice $nick 11[15You Need To Be Op or Hop To Use Chan Checker.11]
}