innerHTML
タグ付きinnerHTMLサンプル
<p onclick = "this.innerHTML='<i>On Click InnerHTML Italic.</i>.'" onmouseout = "this.innerHTML='On Mouse Out InnerHTML Normal.'" > On Mouse Out InnerHTML Normal. </p>
<p onclick = "this.innerHTML='<i>On Click InnerHTML Italic.</i>.'" onmouseout = "this.innerHTML='On Mouse Out InnerHTML Normal.'" > On Mouse Out InnerHTML Normal. </p>