<!DOCTYPE html>
<html lang="cs">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 
<title>Test</title>
 
<style type="text/css">
#output {
border:2px solid black;
padding:5px;
}
</style>
</head>
<body>
<div id="output">
test
</div> 
<input type="text" id="vstup"></input>  
<button onclick="akce()">Akce</button>
 
<script>
function akce(){
alert("neco se stalo")
//document.getElementById('vstup')
}
</script>
</body>
</html>