Logic firtname

#head>
#script>
function warna(x){
document.getElementById(x).style.background="lightblue";
}
#/script>
#/head>
#body>
nama1 = #input type="text" id="n1" onFocus="warna(this.id)"/>
#br/>
nama2 = #input type="text" id="n2"onfocus="warna(this.id)"/>
#br/>
nama3 = #input type="text" id="n3"/>
#input type="button" value="Proses" onClick="document.getElementById('n3').value=document.getElementById('n1').value+document.getElementById('n2').value"/>
#/body>