<input type="password" id="password" name="password" placeholder="请输入密码" onfocus="if(placeholder=='请输入密码') {placeholder=''}" onblur="if (value=='') {placeholder='请输入密码'}">
<input type="tel" id="tel" value="请输入您的电话号码" onfocus="if(value=='请输入您的电话号码') {value=''}" onblur="if (value=='') {value='请输入您的电话号码'}">
placeholder 与 value 区别
placeholder可以用于密码内可见文字提示
value不可