做个假的呗~行不<input type="radio" id='a1'>
<input type="checkbox" id='a2' style="display:none">
<input type="button" onclick="a2.style.display='block';a1.style.display='none';">
<input type="checkbox" id='a2' style="display:none">
<input type="button" onclick="a2.style.display='block';a1.style.display='none';">
<input type=button onclick="chk.outerHTML=chk.outerHTML.replace(/type=radio/,'type=checkbox');alert(chk.outerHTML)" value=修改>