Facebook Auto "Poke Back"

setInterval(function() {
   var el = document.getElementsByClassName("_42ft _4jy0 _4jy3 _4jy1 selected _51sy")
   for (i = 0; i < el.length; i++) {
      if (el[i].innerHTML == '<i class="_3-8_ img sp_MBwkPS_Bdf0 sx_509c5b"></i>Poke Back'){
         el[i].click()
      }
   }
},1000);