<html><body><form>用户名：<input type="text" id="usrname"><br>密码：<input type="password" id="myPsw"></form><br><button onclick="disablePsw()">禁用密码字段</button><button onclick="undisablePsw()">取消禁用密码字段</button><script>function disablePsw() { document.getElementById("myPsw").disabled = true;}function undisablePsw() { document.getElementById("myPsw").disabled = false;}</script></body></html>