<body>
<script>
var btn=document.createElement("input");
btn.type="button";
btn.value="test"
btn.attachEvent("onclick",a)
document.body.appendChild(btn)
function a(){
alert(event.srcElement.value)
}
</script>
</body>
<script>
var btn=document.createElement("input");
btn.type="button";
btn.value="test"
btn.attachEvent("onclick",a)
document.body.appendChild(btn)
function a(){
alert(event.srcElement.value)
}
</script>
</body>
<script>
var btn=document.createElement("input");
btn.type="button";
btn.value="test"
btn.attachEvent("onclick",a)
document.body.appendChild(btn)
function a(){
alert(event.srcElement.value)
}
</script>
</body>
<body>
<script>
var btn=document.createElement("input");
btn.type="button";
document.body.insertAdjacentElement("afterBegin",btn);
btn["onclick"] = function() {alert("you have press me")}
</script>
</body>
</html>