一、表单校验
二、代码实例
1、自定义样式（Custom styles）
<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>
2、浏览器默认（Browser defaults）
<form class="row g-3">
<div class="col-md-4">
<label for="validationDefault01" class="form-label">First name</label>
<input type="text" class="form-control" id="validationDefault01" value="Mark" required>
</div>
<div class="col-md-4">
<label for="validationDefault02" class="form-label">Last name</label>
<input type="text" class="form-control" id="validationDefault02" value="Otto" required>
</div>
<div class="col-md-4">
<label for="validationDefaultUsername" class="form-label">Username</label>
<div class="input-group">
<span class="input-group-text" id="inputGroupPrepend2">@</span>
<input type="text" class="form-control" id="validationDefaultUsername" aria-describedby="inputGroupPrepend2" required>
</div>
</div>
<div class="col-md-6">
<label for="validationDefault03" class="form-label">City</label>
<input type="text" class="form-control" id="validationDefault03" required>
</div>
<div class="col-md-3">
<label for="validationDefault04" class="form-label">State</label>
<select class="form-select" id="validationDefault04" required>
<option selected disabled value="">Choose...</option>
<option>...</option>
</select>
</div>
<div class="col-md-3">
<label for="validationDefault05" class="form-label">Zip</label>
<input type="text" class="form-control" id="validationDefault05" required>
</div>
<div class="col-12">
<div class="form-check">
<input class="form-check-input" type="checkbox" value="" id="invalidCheck2" required>
<label class="form-check-label" for="invalidCheck2">
Agree to terms and conditions
</label>
</div>
</div>
<div class="col-12">
<button class="btn btn-primary" type="submit">Submit form</button>
</div>
</form>
3、服务器端校验（Server side）
<form class="row g-3">
<div class="col-md-4">
<label for="validationServer01" class="form-label">First name</label>
<input type="text" class="form-control is-valid" id="validationServer01" value="Mark" required>
<div class="valid-feedback">
Looks good!
</div>
</div>
<div class="col-md-4">
<label for="validationServer02" class="form-label">Last name</label>
<input type="text" class="form-control is-valid" id="validationServer02" value="Otto" required>
<div class="valid-feedback">
Looks good!
</div>
</div>
<div class="col-md-4">
<label for="validationServerUsername" class="form-label">Username</label>
<div class="input-group has-validation">
<span class="input-group-text" id="inputGroupPrepend3">@</span>
<input type="text" class="form-control is-invalid" id="validationServerUsername" aria-describedby="inputGroupPrepend3 validationServerUsernameFeedback" required>
<div id="validationServerUsernameFeedback" class="invalid-feedback">
Please choose a username.
</div>
</div>
</div>
<div class="col-md-6">
<label for="validationServer03" class="form-label">City</label>
<input type="text" class="form-control is-invalid" id="validationServer03" aria-describedby="validationServer03Feedback" required>
<div id="validationServer03Feedback" class="invalid-feedback">
Please provide a valid city.
</div>
</div>
<div class="col-md-3">
<label for="validationServer04" class="form-label">State</label>
<select class="form-select is-invalid" id="validationServer04" aria-describedby="validationServer04Feedback" required>
<option selected disabled value="">Choose...</option>
<option>...</option>
</select>
<div id="validationServer04Feedback" class="invalid-feedback">
Please select a valid state.
</div>
</div>
<div class="col-md-3">
<label for="validationServer05" class="form-label">Zip</label>
<input type="text" class="form-control is-invalid" id="validationServer05" aria-describedby="validationServer05Feedback" required>
<div id="validationServer05Feedback" class="invalid-feedback">
Please provide a valid zip.
</div>
</div>
<div class="col-12">
<div class="form-check">
<input class="form-check-input is-invalid" type="checkbox" value="" id="invalidCheck3" aria-describedby="invalidCheck3Feedback" required>
<label class="form-check-label" for="invalidCheck3">
Agree to terms and conditions
</label>
<div id="invalidCheck3Feedback" 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>
4、支持的元素（Supported elements）
<form class="was-validated">
<div class="mb-3">
<label for="validationTextarea" class="form-label">Textarea</label>
<textarea class="form-control is-invalid" id="validationTextarea" placeholder="Required example textarea" required></textarea>
<div class="invalid-feedback">
Please enter a message in the textarea.
</div>
</div>
<div class="form-check mb-3">
<input type="checkbox" class="form-check-input" id="validationFormCheck1" required>
<label class="form-check-label" for="validationFormCheck1">Check this checkbox</label>
<div class="invalid-feedback">Example invalid feedback text</div>
</div>
<div class="form-check">
<input type="radio" class="form-check-input" id="validationFormCheck2" name="radio-stacked" required>
<label class="form-check-label" for="validationFormCheck2">Toggle this radio</label>
</div>
<div class="form-check mb-3">
<input type="radio" class="form-check-input" id="validationFormCheck3" name="radio-stacked" required>
<label class="form-check-label" for="validationFormCheck3">Or toggle this other radio</label>
<div class="invalid-feedback">More example invalid feedback text</div>
</div>
<div class="mb-3">
<select class="form-select" required aria-label="select example">
<option value="">Open this select menu</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
</select>
<div class="invalid-feedback">Example invalid select feedback</div>
</div>
<div class="mb-3">
<input type="file" class="form-control" aria-label="file example" required>
<div class="invalid-feedback">Example invalid form file feedback</div>
</div>
<div class="mb-3">
<button class="btn btn-primary" type="submit" disabled>Submit form</button>
</div>
</form>
5、提示（Tooltips）
<form class="row g-3 needs-validation" novalidate>
<div class="col-md-4 position-relative">
<label for="validationTooltip01" class="form-label">First name</label>
<input type="text" class="form-control" id="validationTooltip01" value="Mark" required>
<div class="valid-tooltip">
Looks good!
</div>
</div>
<div class="col-md-4 position-relative">
<label for="validationTooltip02" class="form-label">Last name</label>
<input type="text" class="form-control" id="validationTooltip02" value="Otto" required>
<div class="valid-tooltip">
Looks good!
</div>
</div>
<div class="col-md-4 position-relative">
<label for="validationTooltipUsername" class="form-label">Username</label>
<div class="input-group has-validation">
<span class="input-group-text" id="validationTooltipUsernamePrepend">@</span>
<input type="text" class="form-control" id="validationTooltipUsername" aria-describedby="validationTooltipUsernamePrepend" required>
<div class="invalid-tooltip">
Please choose a unique and valid username.
</div>
</div>
</div>
<div class="col-md-6 position-relative">
<label for="validationTooltip03" class="form-label">City</label>
<input type="text" class="form-control" id="validationTooltip03" required>
<div class="invalid-tooltip">
Please provide a valid city.
</div>
</div>
<div class="col-md-3 position-relative">
<label for="validationTooltip04" class="form-label">State</label>
<select class="form-select" id="validationTooltip04" required>
<option selected disabled value="">Choose...</option>
<option>...</option>
</select>
<div class="invalid-tooltip">
Please select a valid state.
</div>
</div>
<div class="col-md-3 position-relative">
<label for="validationTooltip05" class="form-label">Zip</label>
<input type="text" class="form-control" id="validationTooltip05" required>
<div class="invalid-tooltip">
Please provide a valid zip.
</div>
</div>
<div class="col-12">
<button class="btn btn-primary" type="submit">Submit form</button>
</div>
</form>
