理解innerText，outerText，innerHTML，outerHTML

<div id="div"><input name="button" value="Button" type="button"><font color="green"><h2>This is a DIV!</h2></font></div>
<input name="innerHTML" value="innerHTML" type="button" OnClick="alert(div.innerHTML);">
<input name="outerHTML" value="outerHTML" type="button" OnClick="alert(div.outerHTML);">
<input name="innerText" value="innerText" type="button" OnClick="alert(div.innerText);">
<input name="outerText" value="outerText" type="button" OnClick="alert(div.outerText);">