<html>
<body>
E-mail: <input type="email" id="myEmail" value="johndoe@example.com">
<p>点击按钮修改 email 字段的邮件地址</p>
<button onclick="myFunction()">点我</button>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementById("myEmail").value = "steve@ziqiangxuetang.com";
}
</script>
</body>
</html>