This article illustrates how jQuery monitors text box events and handles them accordingly. Share with you for your reference. The details are as follows:

// Things entrusted
$(document)
 .on('input propertychange', '#query', function(){
  var input = $(this).val();
  show(input);
 });
 var show = function(txt){
  var info = ' Listening: <b>' + txt + '</b><br /><br />'
  + ' Related search: <br />' + showTags(txt);
  $('.info').html(info);
 }
 var showTags = function(txt){
  var tag = '';
  if(txt.length){
   for (var i = 0; i < 3; i++) {
    tag += '<span class="tag">'+txt+' related '+i+'</span>';
   };
  }
  return tag;
}

I hope this article has been helpful to your jQuery programming.