danhorst/activate-required-field.html

## activate-required-field.html
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Toggle field requirement</title>
  <meta name="description" content="A clean-room implmentation of conditional field requirement.">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
  <script>
    $(function() {
      $('#no-doi, #mint-doi').change(function(e){
        var $target = $(e.target),
            $field  = $('#publisher')

        if ($target.attr('id') == 'mint-doi') {
          $field.attr('required', 'true');
        } else {
          $field.removeAttr('required');
        }
      });
    });
  </script>
  <style>
    fieldset {margin:1em 0}
    form {max-width:30em}
    label {display:block}
  </style>
</head>
<body>

<form action="/">
  <fieldset>
    <legend>Create Work</legend>

    <div>
      <label for="title">Title</label>
      <input id="title" name="title" required="true"/>
    </div>

    <div>
      <label for="publisher">Publisher</label>
      <input id="publisher" name="publisher"/>
    </div>

    <fieldset>
      <legend>DOI</legend>
      <label for="no-doi">
        <input type="radio" name="doi" id="no-doi" checked="checked"/>
        I don't need a DOI
      </label>
      <label>
        <input type="radio" name="doi" id="mint-doi"/>
        Create a DOI for me
      </label>
    </fieldset>

    <input type="submit" value="Submit"/>
  </fieldset>
</form>

</body>
</html>
	<!doctype html>
	<html lang="en">
	<head>
	<meta charset="utf-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<title>Toggle field requirement</title>
	<meta name="description" content="A clean-room implmentation of conditional field requirement.">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
	<script>
	$(function() {
	$('#no-doi, #mint-doi').change(function(e){
	var $target = $(e.target),
	$field = $('#publisher')

	if ($target.attr('id') == 'mint-doi') {
	$field.attr('required', 'true');
	} else {
	$field.removeAttr('required');
	}
	});
	});
	</script>
	<style>
	fieldset {margin:1em 0}
	form {max-width:30em}
	label {display:block}
	</style>
	</head>
	<body>

	<form action="/">
	<fieldset>
	<legend>Create Work</legend>

	<div>
	<label for="title">Title</label>
	<input id="title" name="title" required="true"/>
	</div>

	<div>
	<label for="publisher">Publisher</label>
	<input id="publisher" name="publisher"/>
	</div>

	<fieldset>
	<legend>DOI</legend>
	<label for="no-doi">
	<input type="radio" name="doi" id="no-doi" checked="checked"/>
	I don't need a DOI
	</label>
	<label>
	<input type="radio" name="doi" id="mint-doi"/>
	Create a DOI for me
	</label>
	</fieldset>

	<input type="submit" value="Submit"/>
	</fieldset>
	</form>

	</body>
	</html>