решение
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>HTML5</title>
<!--[if IE]>
<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<style>
article, aside, details, figcaption, figure, footer,header,
hgroup, menu, nav, section { display: block; }
</style>
</head>
<body>
<p>Привет, мир</p>
<script>
function vvod()
{
//alert("111");
//console.log(document.head);
//window.innerHTML= '11111111111';
document.head.innerHTML= '<head>11111111111</head>';
}
</script>
<input onFocus = "vvod();" />
</body>
</html>