add a checkbox in html code example

Example 1: html checkbox

<!--
  You can group and post different values with the same "name".
  When posted to PHP, all checked boxes' values will appear under
  the "peripherals" element in `$_POST` array.
  E.g. if we check "screen" & "keyboard" and post the form then
  `$_POST` will contain `['peripherals' => ['screen', 'keyboard']]`
-->
<form>
  <input type="checkbox" id="periph1" name="peripherals" value="screen">
  <label for="periph1"> I have a Screen</label>
  <input type="checkbox" id="periph2" name="peripherals" value="keyboard">
  <label for="periph2"> I have a Keyboard</label>
  <input type="checkbox" id="periph3" name="peripherals" value="mouse">
  <label for="periph3"> I have a Mouse</label>
  <button type="submit">Send</button>
</form>

Example 2: html checkbox status

app.innerHTML = '<h1>Hello, world!</h1>';