<input type="text" name="usr_name" required='required' oninvalid="setCustomValidity('warning')" oninput="setCustomValidity('')" />
<input type="text" name="usr_name" required='required' oninvalid="setCustomValidity('warning')" oninput="setCustomValidity('')" />
转载于:https://www.cnblogs.com/gengaixue/p/4882196.html