javascript - 删除 :focus/control generated error field 上的输入文本

Question

好的，所以这是一个两部分的问题

fiddle :http://jsfiddle.net/aujqU/575/

问题 1:我这里有这个表格，当我选择该字段时不会删除输入文本。我认为它可能是“占位符”标签。然后我在这里阅读了与“占位符”相关的其他问题，发现它为此赋予了 HTML5 功能，但显然这在这里不起作用。我正在使用 jQuery 验证表单。

问题 2:当用户没有输入所需信息时，jQuery 将生成一个“label:error”字段，可以按照我想要的方式设置样式。当表单填写不当时，它不会填充错误字段。它只是给出浏览器的默认值。有什么想法……？

<div id="form-frame">
     <h3>Schedule a Free Security Review</h3>

    <p>Fill out the form and a Security Specialist will contact you at the phone number below about offers.</p>
    <p>All fields required.</p>
    <form id="contactForm" method="POST" action="">
        <input type="text" id="first_name" name="first_name" minlength="5" maxlength="255" placeholder="First Name" value="" required />
        <input type="text" id="last_name" name="last_name" minlength="2" maxlength="255" placeholder="Last Name" value="" required />
        <input type="hidden" id="state" name="state" value="" />
        <input type="text" id="email" name="email" minlength="25" maxlength="255" placeholder="Email" value="" required />
        <input type="text" id="postal_code" name="postal_code" minlength="5" maxlength="10" placeholder="Zip Code" value="" required />
        <input type="text" id="phone_primary" name="phone_primary" minlength="11" maxlength="12" placeholder="Phone" value="" required />
        <input type="submit" value="Submit" />
    </form>
     <h6>* I agree to receive telemarketing calls at the telephone number provided above.</h6>

    <p>Or Call Us At <span> 888-888-8888</span>

    </p>
</div>

 $('#contactForm').validate({
     onfocusout: function (element) {
         this.element(element);
     },
     rules: {
         first_name: 'required',
         last_name: 'required',
         state: 'required',
         email: 'required',
         postal_code: 'required',
         phone_primary: 'required'
     },
     messages: {
         first_name: 'Please enter your first name',
         last_name: 'Please enter your last name',
         email: 'Please enter your email',
         postal_code: 'Please enter your zip code',
         phone_primary: 'Please enter your phone number'
     }
 });

Answer 1

广告。问题 1:正如评论中的人所说，这取决于浏览器。根据latest W3C spec draft :

User agents should present this hint to the user [...] e.g. by displaying it inside a blank unfocused control and hiding it otherwise.

不幸的是，并非所有浏览器都遵循此建议，例如当一个字段获得焦点时，最新版本的 Chrome 不会隐藏占位符。当然，您可以使用 Javascript 来处理。

但是，请记住这是对占位符的一种滥用，因为(同样，根据规范)它们应该用作提示，而不是标签。

广告。问题 2:这已被回答过几次，例如here .请查看代码的改进版本 here on jsfiddle :

// Problem no.2 - added http://ajax.aspnetcdn.com/ajax/jquery.validate/1.13.0/jquery.validate.min.js to the "External resources" in jsfiddle and it started working as expected
$('#contactForm').validate({
     onfocusout: function (element) {
         this.element(element);
     },
     rules: {
         first_name: 'required',
         last_name: 'required',
         state: 'required',
         email: 'required',
         postal_code: 'required',
         phone_primary: 'required'
     },
     messages: {
         first_name: 'Please enter your first name',
         last_name: 'Please enter your last name',
         email: 'Please enter your email',
         postal_code: 'Please enter your zip code',
         phone_primary: 'Please enter your phone number'
     }
 });

// Problem no. 1
$('input[type=text]').focus(function () {
    this['data-placeholder_old'] = this.placeholder;
    this.placeholder = '';
});

$('input[type=text]').blur(function () {
    this.placeholder = this['data-placeholder_old'] || '';
})

为了进行验证，我只将 jquery.validate 插件附加到 fiddle 上。