JQUERY event handler and listener

<script>
$( "#btnsubmit" ).click(function() {
  alert(this.form.ket.value)
  return false
})
</script>document.getElementById("oprevent").addEventListener("click", function(event){
  $.post("?mustahiq=<? echo $_GET[mustahiq]?>&txt&act=save",$(this.form).serialize()).done(function(response){
    //var wnd = window.open("about:blank", "", "_blank")
    //wnd.document.write(response)

    var node = response.split("<<<")
    console.log(response.split("||")Ώ])
    if(nodeΏ]==" ok "){alert('data telah tersimpan')location.reload(true)}
  })  
  event.preventDefault()
})


<button type='submit' id='btnsubmit' onclick='return false'>OK</button>
<script>
$( "#btnsubmit" ).click(function() {
  alert(this.form.ket.value)
  return false
})
</script>