<form>
<input type="email" placeholder="Enter your email">
<input type="submit" value="Submit">
</form>
添加必需的属性
<input type="email" placeholder="Enter your email" required>
在回答第二个问题时,您可以设置title属性,该属性将文本附加到默认错误消息。为了完全自定义错误消息,您需要编写一些JavaScript。您想要侦听“无效”事件,并使用setCustomValidity设置消息
input.addEventListener('invalid', function(e) {
if (input.validity.valueMissing) {
e.target.setCustomValidity("PLZ CREATE A USERNAME, YO!");
} else if(!input.validity.valid) {
e.target.setCustomValidity("U R DOIN IT WRONG!");
}
}, false);
见:http://developer.nokia.com/Blogs/Code/2012/11/21/creating-a-custom-html5-form-validation/
以及自定义所需的消息
HTML5 form required attribute. Set custom validation message?