bootstrap form error message code example
Example 1: bootstrap input field validation
<form>
<div class="form-row">
<div class="col-md-4 mb-3">
<label for="validationServer01">First name</label>
<input type="text" class="form-control is-valid" id="validationServer01" placeholder="First name" value="Mark" required>
<div class="valid-feedback">
Looks good!
</div>
</div>
<div class="col-md-4 mb-3">
<label for="validationServer02">Last name</label>
<input type="text" class="form-control is-valid" id="validationServer02" placeholder="Last name" value="Otto" required>
<div class="valid-feedback">
Looks good!
</div>
</div>
<div class="col-md-4 mb-3">
<label for="validationServerUsername">Username</label>
<div class="input-group">
<div class="input-group-prepend">
<span class="input-group-text" id="inputGroupPrepend3">@</span>
</div>
<input type="text" class="form-control is-invalid" id="validationServerUsername" placeholder="Username" aria-describedby="inputGroupPrepend3" required>
<div class="invalid-feedback">
Please choose a username.
</div>
</div>
</div>
</div>
<div class="form-row">
<div class="col-md-6 mb-3">
<label for="validationServer03">City</label>
<input type="text" class="form-control is-invalid" id="validationServer03" placeholder="City" required>
<div class="invalid-feedback">
Please provide a valid city.
</div>
</div>
<div class="col-md-3 mb-3">
<label for="validationServer04">State</label>
<input type="text" class="form-control is-invalid" id="validationServer04" placeholder="State" required>
<div class="invalid-feedback">
Please provide a valid state.
</div>
</div>
<div class="col-md-3 mb-3">
<label for="validationServer05">Zip</label>
<input type="text" class="form-control is-invalid" id="validationServer05" placeholder="Zip" required>
<div class="invalid-feedback">
Please provide a valid zip.
</div>
</div>
</div>
<div class="form-group">
<div class="form-check">
<input class="form-check-input is-invalid" type="checkbox" value="" id="invalidCheck3" required>
<label class="form-check-label" for="invalidCheck3">
Agree to terms and conditions
</label>
<div class="invalid-feedback">
You must agree before submitting.
</div>
</div>
</div>
<button class="btn btn-primary" type="submit">Submit form</button>
</form>
Example 2: bootstrap email address validation
<form> <!--make sure you add this inside a form-->
<div class="form-group"> <!--required to start the form container-->
<label for="InputEmail">Email address</label> <!--"for" needs to match the "id" on the next line to bind it-->
<input type="email" class="form-control" id="InputEmail" placeholder="Enter email"> <!--id, class, and type are required for it too look right, placeholder will edit the text inside the input box-->
<small class="form-text">We'll never share your info.</small> <!--applies small underlining text-->
</div>
<div class="form-group">
<label for="Password">Password</label>
<input type="password" class="form-control" id="Password" placeholder="Password">
</div>
<div class="form-check">
<input type="checkbox" class="form-check-input" id="Check">
<label class="form-check-label" for="Check">Check out</label>
</div>
<button type="submit" class="btn btn-primary">Submit</button>
</form>