<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.2/jquery.min.js"></script>
<script>
$(document).ready(function(){
$("input").keydown(function(){
$("input").css("background-color", "lightblue");
});
$("input").keyup(function(){
$("input").css("background-color", "lavender");
});
$("#btn1").click(function(){
$("input").keydown();
});
$("#btn2").click(function(){
$("input").keyup();
});
});
</script>
</head>
<body>
<input type="text">
<p><button id="btn1">Trigger keydown event for input field</button></p>
<p><button id="btn2">Trigger keyup event for input field</button></p>
</body>
</html>