Untitled

<html>
<head>
<script>
function func()
{
var elem=document.createElement("input");
document.body.appendChild(elem);
elem.setAttribute('type','text');
}
</script>
</head>
<body>
<p>Hey guys!<p>
<input type="button" value="push" onclick="func()"/>
<script>
func();
</script>
<p>Hey girls!<p>
</body>
</html>

document.body.insertBefore( elem, document.getElementsByTagName('p')[1] );

function func() {
    var elem = document.createElement("input");
    elem.setAttribute('type','text');
    var ps = document.getElementsByTagName("p");
    if (ps.length < 2)
        return; // abort! we didn't find our element
    var p = ps[1];
    document.body.insertBefore(elem, p);
}