5-7-3 bootstrap5 - 表單驗證提示

自定義樣式

參考：https://bootstrap5.hexschool.com/docs/5.1/forms/validation/

為了自定義 Bootstrap 表單驗證訊息，您需要將布林屬性 novalidate 添加到 <form> 中。這將會禁用瀏覽器預設的回饋工具提示，不過 JavaScript 的表單驗證 API 依然有效。嘗試提交以下的表單，Bootstrap 的 JavaScript 將會攔截提交按鈕並向您提供回饋。在嘗試提交時，您會看到 :invalid 和 :valid 的樣式被應用於您的表單控制元件。

但仍提供 JavaScript 中表單驗證 API 有效。嘗試提交以下表格；我們的 JavaScript 將攔截提交按鈕並向您提供回饋。嘗試提交時，您會看到 :invalid 和 :valid 的樣式應用於表單控制元件 (form control)。

自定義的回饋樣式將會採用客製化的顏色、邊界、focus 樣式和背景圖示以更好的傳遞回饋。<select> 的背景圖示僅適用於 .form-select 而不可使用於 .form-control。

<form class="row g-3 needs-validation" novalidate>
  <div class="col-md-4">
    <label for="validationCustom01" class="form-label">First name</label>
    <input type="text" class="form-control" id="validationCustom01" value="Mark" required>
    <div class="valid-feedback">
      Looks good!
    </div>
  </div>
  <div class="col-md-4">
    <label for="validationCustom02" class="form-label">Last name</label>
    <input type="text" class="form-control" id="validationCustom02" value="Otto" required>
    <div class="valid-feedback">
      Looks good!
    </div>
  </div>
  <div class="col-md-4">
    <label for="validationCustomUsername" class="form-label">Username</label>
    <div class="input-group has-validation">
      <span class="input-group-text" id="inputGroupPrepend">@</span>
      <input type="text" class="form-control" id="validationCustomUsername" aria-describedby="inputGroupPrepend" required>
      <div class="invalid-feedback">
        Please choose a username.
      </div>
    </div>
  </div>
  <div class="col-md-6">
    <label for="validationCustom03" class="form-label">City</label>
    <input type="text" class="form-control" id="validationCustom03" required>
    <div class="invalid-feedback">
      Please provide a valid city.
    </div>
  </div>
  <div class="col-md-3">
    <label for="validationCustom04" class="form-label">State</label>
    <select class="form-select" id="validationCustom04" required>
      <option selected disabled value="">Choose...</option>
      <option>...</option>
    </select>
    <div class="invalid-feedback">
      Please select a valid state.
    </div>
  </div>
  <div class="col-md-3">
    <label for="validationCustom05" class="form-label">Zip</label>
    <input type="text" class="form-control" id="validationCustom05" required>
    <div class="invalid-feedback">
      Please provide a valid zip.
    </div>
  </div>
  <div class="col-12">
    <div class="form-check">
      <input class="form-check-input" type="checkbox" value="" id="invalidCheck" required>
      <label class="form-check-label" for="invalidCheck">
        Agree to terms and conditions
      </label>
      <div class="invalid-feedback">
        You must agree before submitting.
      </div>
    </div>
  </div>
  <div class="col-12">
    <button class="btn btn-primary" type="submit">Submit form</button>
  </div>
</form>

JS

  <script>
    // Example starter JavaScript for disabling form submissions if there are invalid fields
    (function() {
      'use strict'

      // Fetch all the forms we want to apply custom Bootstrap validation styles to
      var forms = document.querySelectorAll('.needs-validation')

      // Loop over them and prevent submission
      Array.prototype.slice.call(forms)
        .forEach(function(form) {
          form.addEventListener('submit', function(event) {
            if (!form.checkValidity()) {
              event.preventDefault()
              event.stopPropagation()
            }

            form.classList.add('was-validated')
          }, false)
        })
    })()
  </script>