<!DOCTYPE html>
<html lang="ja-JP">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,user-scalable=yes,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.5">
<title></title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script>
$(function(){
$("input").click(function(){
$("span").text($("div").html());
//以下の記述も可
//$("span").text(document.getElementsByTagName("div")[0].innerHTML);
//document.getElementsByTagName("span")[0].innerText = $("div").html();
//document.getElementsByTagName("span")[0].innerText = document.getElementsByTagName("div")[0].innerHTML;
});
});
</script>
</head>
<body>
<div><strong>テキスト</strong><em>テキスト</em><ins>テキスト</ins><del>テキスト</del></div>
<span></span>
<input type="button" value="click">
</body>
</html>