<!DOCTYPE html>
<html>
<head>
<script>
function changeTabIndex()
{document.getElementById('1').tabIndex="3";document.getElementById('2').tabIndex="2";document.getElementById('3').tabIndex="1";}
</script>
</head>
<body>
<p><a id="1" href="https://www.w3school.org.cn">1</a></p>
<p><a id="2" href="https://www.w3school.org.cn">2</a></p>
<p><a id="3" href="https://www.w3school.org.cn">3</a></p>
<input type="button" onclick="changeTabIndex()"
value="更改 TabIndex">
<p>请在按下 “更改 TabIndex” 按钮前后事宜 tab 键在链接间导航。</p>
</body>
</html>