<html>
<head>
<title>titulo</title>
<script type="text/javascript">
function nodos() {
var parrafos = document.getElementsByTagName("p");
var ver = document.write(parrafos[0]);
</script>
</head>
<body>
<p>Lorem ipsum dolor sit ametonsectetuer adipiscing elit vitae orci. Phasellus libero. Maecenas nisl arcu, consequat congue</p>
<p>Aenean at nisl. Maecenalum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Proin consequat au</p>
<p> sit amet diam. Curabitur hendrerit, eros quis malesuada tristique, ipsum odio euismod tortor, a vestibulum nisl mi at o.</p>
<input type="button" value="ver" onClick="nodos()">
</body>
</html>