O elemento button: submit, reset e button

O elemento button

<button type="submit">Submit</button>
<button type="reset">Clear Form</button>
<button type="button">Do Something</button>

<!-- Three types, each with a different default behavior -->
<!-- Always specify type — the default is submit inside forms -->

type=submit

<form action="/register" method="post">
  <input type="email" name="email">
  <button type="submit">Create Account</button>
</form>
<!-- Triggers form validation, then sends the form data -->
<!-- Also triggered by pressing Enter in most text inputs -->

type=reset

<form>
  <input type="text" name="name" value="">  <!-- empty default -->
  <input type="number" name="qty" value="1">  <!-- default: 1 -->
  <button type="reset">Clear</button>
</form>
<!-- Clicking reset restores qty to 1 and clears name -->
<!-- Use sparingly — users often accidentally reset forms -->

type=button

<button type="button" id="toggle-theme">Toggle Dark Mode</button>

<script>
document.getElementById('toggle-theme').addEventListener('click', () => {
  document.body.classList.toggle('dark');
});
</script>
<!-- type="button" prevents accidental form submission
     Always use this for non-submit buttons -->

button versus input[type=submit]

<!-- Old way (limited): -->
<input type="submit" value="Submit">

<!-- Modern way (flexible — can contain HTML): -->
<button type="submit">
  <svg><!-- icon --></svg>
  Submit Form
</button>
<!-- button can contain icons, emphasis, and any inline HTML
     input type=submit can only have plain text via the value attribute -->

Botão desativado

<button type="submit" disabled>Submit</button>
<!-- Disabled buttons:
  - Cannot be clicked
  - Not in tab order
  - NOT submitted with the form
  - Browser renders them grayed out -->

<!-- Enable/disable with JavaScript: -->
btn.disabled = true;
btn.disabled = false;

Padrão de estado de carregamento

<button type="submit" id="submit-btn">
  <span id="btn-text">Submit</span>
  <span id="btn-spinner" hidden aria-hidden="true">⏳</span>
</button>

<script>
form.addEventListener('submit', () => {
  document.getElementById('submit-btn').disabled = true;
  document.getElementById('btn-text').textContent = 'Submitting...';
  document.getElementById('btn-spinner').hidden = false;
  document.getElementById('btn-spinner').removeAttribute('aria-hidden');
});
</script>

Substituições de ação e método do formulário

<form action="/save" method="post">
  <input type="text" name="title">

  <!-- Save: uses form defaults -->
  <button type="submit">Save Draft</button>

  <!-- Publish: overrides action and method -->
  <button type="submit" formaction="/publish" formmethod="post">
    Publish Now
  </button>
</form>

Botão com ARIA

<!-- Icon-only button -->
<button type="button" aria-label="Close dialog">
  <svg aria-hidden="true"><!-- X icon --></svg>
</button>

<!-- Toggle button -->
<button type="button" aria-pressed="false" id="bold-btn">
  Bold
</button>
<script>
document.getElementById('bold-btn').addEventListener('click', function() {
  const pressed = this.getAttribute('aria-pressed') === 'true';
  this.setAttribute('aria-pressed', !pressed);
});
</script>

Boas práticas de acessibilidade para botões

Área de clique e alvos de toque

button {
  min-height: 44px;   /* Apple HIG minimum */
  min-width: 44px;    /* WCAG 2.5.5 (AAA) recommends 44x44 -->
  padding: 0.5rem 1rem;
  cursor: pointer;
}

/* Increase tap area without changing visual size: */
button {
  position: relative;
}
button::before {
  content: '';
  position: absolute;
  inset: -8px;
}

Verificação rápida

Recapitulação: elemento button