bootstrap4 表单验证——迹忆客-ag捕鱼王app官网

bootstrap4 提供了一种在客户端验证 web 表单的简单的方法。

bootstrap4 使用浏览器的原生表单验证 api 来验证表单。

表单验证样式通过 css的伪类 :invalid 和 :valid 应用到标签上。 它适用于 、 元素。</p> <p>让我们试试下面的例子，看看它是如何工作的：</p> <blockquote class="alert alert-info"> <pre><code class="language-html"><form class="needs-validation" novalidate> <div class="mb-3"> <label class="form-label" for="inputemail">email</label> <input type="email" class="form-control" id="inputemail" placeholder="email" required> <div class="invalid-feedback">请输入有效的邮件地址。</div> </div> <div class="mb-3"> <label class="form-label" for="inputpassword">password</label> <input type="password" class="form-control" id="inputpassword" placeholder="password" required> <div class="invalid-feedback">密码不能为空</div> </div> <div class="mb-3"> <div class="form-check"> <input class="form-check-input" type="checkbox" id="checkremember"> <label class="form-check-label" for="checkremember">记住我</label> </div> </div> <button type="submit" class="btn btn-primary">登录</button> </form> </code></pre> </blockquote> <blockquote class="alert alert-warning"> <p><strong><code>注意</code></strong> ：对于自定义 bootstrap 表单验证消息，我们需要通过向 <form> 元素添加 <strong>novalidate</strong> 布尔属性来禁用浏览器默认的反馈提示。 但是，它仍然提供对 javascript 中表单验证 api 的访问。</p> </blockquote> <p>下面是显示错误消息并在存在无效字段时禁用表单提交的自定义 javascript 代码。 请参阅 <a href="/tm/xwzj/web_83.html" target="_blank">javascript 闭包</a>章节来了解执行函数。</p> <blockquote class="alert alert-info"> <pre><code class="language-javascript"> // self-executing function (function() { 'use strict'; window.addeventlistener('load', function() { // fetch all the forms we want to apply custom bootstrap validation styles to var forms = document.getelementsbyclassname('needs-validation'); // loop over them and prevent submission var validation = array.prototype.filter.call(forms, function(form) { form.addeventlistener('submit', function(event) { if (form.checkvalidity() === false) { event.preventdefault(); event.stoppropagation(); } form.classlist.add('was-validated'); }, false); }); }, false); })(); </code></pre> <p><a href='https://tools.jiyik.com/try_code/bootstrap4_form_validation' class='run-code' target='_blank'>尝试一下</a></p> </blockquote> <p>上面示例输出结果如下</p> <p><img src="/uploads/211120/i_202111201000222a5b97.gif" alt="bootstrap4 表单验证"></p> <blockquote class="alert alert-warning"> <p><strong><code>提示</code></strong> ：要想动态重置表单的样式，需要在提交后从 <form> 元素中删除 <strong>.was-validated</strong> 类。 当单击提交按钮时，bootstrap4 会自动在表单上应用此类。</p> </blockquote> <p>如果需要服务器端进行验证，也可以使用 <code>.is-invalid</code> 和 <code>.is-valid</code> 类来表示验证通过或者未通过的表单字段。 除此之外也可以使用 <code>.invalid-feedback</code> 和 <code>.valid-feedback</code> 。 让我们看一下下面的例子：</p> <blockquote class="alert alert-info"> <pre><code class="language-html"><form> <div class="mb-3"> <label class="form-label" for="inputemail">email</label> <input type="email" class="form-control is-valid" id="inputemail" placeholder="email" value="peterparker@example.com" required> <div class="valid-feedback">good! 您的邮件地址看起来是有效的。</div> </div> <div class="mb-3"> <label class="form-label" for="inputpassword">password</label> <input type="password" class="form-control is-invalid" id="inputpassword" placeholder="password" required> <div class="invalid-feedback">opps! 您的密码好像不对哦。</div> </div> <div class="mb-3"> <div class="form-check"> <input class="form-check-input" type="checkbox" id="checkremember"> <label class="form-check-label" for="checkremember">记住我</label> </div> </div> <button type="submit" class="btn btn-primary">登录</button> </form> </code></pre> <p><a href='https://tools.jiyik.com/try_code/bootstrap4_server_validate_form' class='run-code' target='_blank'>尝试一下</a></p> </blockquote> <p>上面示例输出结果如下</p> <p><img src="/uploads/211120/i_20211120100809432c4f.jpg" alt="bootstrap4 服务端验证表单"></p> <p>我们也可以将 <code>.{valid|invalid}-feedback</code> 类替换为 <code>.{valid|invalid}-tooltip</code> 类，以不同的样式显示反馈的文本。</p> <p>此外，请务必在父元素上应用样式 <code>position:relative</code> 或 class <code>.position-relative</code> 以获得正确的反馈提示定位。 下面是一个例子：</p> <blockquote class="alert alert-info"> <pre><code class="language-html"><form> <div class="mb-3 position-relative"> <label class="form-label" for="inputemail">email</label> <input type="email" class="form-control is-valid" id="inputemail" placeholder="email" value="jiyi_onmpw@jiyik.com" required> <div class="valid-tooltip">good! 您的邮件地址看起来是有效的。</div> </div> <div class="mb-3 position-relative"> <label class="form-label" for="inputpassword">password</label> <input type="password" class="form-control is-invalid" id="inputpassword" placeholder="password" required> <div class="invalid-tooltip">opps! 您的密码好像不对哦。</div> </div> <div class="mb-3"> <div class="form-check"> <input class="form-check-input" type="checkbox" id="checkremember"> <label class="form-check-label" for="checkremember">记住我</label> </div> </div> <button type="submit" class="btn btn-primary">登录</button> </form> </code></pre> <p><a href='https://tools.jiyik.com/try_code/bootstrap4_tooltip_form_validate' class='run-code' target='_blank'>尝试一下</a></p> </blockquote> 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