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Bs5 Form Validation in Bootstrap

Bs5 Form Validation in Bootstrap

Sure! Here's a clear guide on Bootstrap 5 (BS5) Form Validation — built-in styles and behaviors to help you validate user inputs with visual feedback.


? How BS5 Form Validation Works

Bootstrap 5 uses HTML5 form validation APIs enhanced with its own CSS classes to show validation states like success or error. You just need to:

  • Use native HTML validation attributes (required, pattern, type, etc.)

  • Add Bootstrap validation classes dynamically or via JavaScript

  • Style feedback messages with Bootstrap classes


? Basic Setup with HTML5 Validation

Add the novalidate attribute to the <form> tag to prevent default browser tooltips, then use Bootstrap's classes and feedback:

<form class="needs-validation" novalidate>  <div class="mb-3">    <label for="validationCustom01" class="form-label">First name</label>    <input type="text" class="form-control" id="validationCustom01" value="" required>    <div class="valid-feedback">      Looks good!    </div>    <div class="invalid-feedback">      Please provide a first name.    </div>  </div>  <button class="btn btn-primary" type="submit">Submit form</button></form>
  • needs-validation: used to identify forms that need validation

  • .valid-feedback and .invalid-feedback: messages shown on validation states


? JavaScript to Trigger Validation Styles

You need JavaScript to toggle .was-validated on the form after submit:

(() => {  'use strict'  const forms = document.querySelectorAll('.needs-validation')  Array.from(forms).forEach(form => {    form.addEventListener('submit', event => {      if (!form.checkValidity()) {        event.preventDefault()        event.stopPropagation()      }      form.classList.add('was-validated')    }, false)  })})()
  • form.checkValidity() uses the browser's native validation

  • Adding .was-validated triggers Bootstrap styles


? Validation States

ClassDescription
.is-validApplied to inputs when valid
.is-invalidApplied to inputs when invalid
.valid-feedbackMessage shown when input valid
.invalid-feedbackMessage shown when input invalid

? Example with Custom Validation

<form class="needs-validation" novalidate>  <input type="email" class="form-control" id="email" required>  <div class="invalid-feedback">    Please enter a valid email address.  </div>  <button type="submit" class="btn btn-primary mt-3">Submit</button></form>

Use the same JS snippet above to enable validation feedback.


? Browser Support and Limitations

  • Uses built-in HTML5 validation — so support depends on browsers.

  • You can add your own custom validations via JavaScript if needed.


Would you like a full example with multiple inputs, or details on custom validation methods?

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