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CSS

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HTML 

              
                <h1>Demo</h1>
<p>The form below demoes a pattern where each question has its own <strong>live region</strong>, which errors are inserted into.</p>
<p>Its <code>validate()</code> is set up to always return false. This is on purpose and just for the demo.</p>
<p>Some notes/tips:</p>
<ul>
  <li>Make sure your error area is associated with your input (by putting it inside the label or by associating it with <code>aria-labelledby</code>)</li>
  <li>Best keep your labels short.</li>
  <li>You can also group your errors in one live region instead of having errors with each field.</li>
  <li>You can also group your errors at the top of the page, not use a live region and give the error area focus when someone tries to submit a form that has errors according to your script.</li>
</ul>
<form action="">
  <div class="question">
    <label for="question-1" id="label-1">What is your name? <em>Note, when you leave the field an error will appear in an explicit live region (assertive)</em></label>
    <input type="text" id="question-1" data-error="That's not a name" aria-labelledby="label-1 error-area-1" />
    <div aria-live="assertive" aria-relevant="additions removals" class="error-area" id="error-area-1">
    <!-- insert error messages here -->
    </div> 
  </div>
  <div class="question">
    <label for="question-2" id="label-2">Where do you live? <em>Note, when you leave the field, an error will appear in a role=alert, which should behave like a live region</em></label>
    <input type="text" id="question-2" data-error="That's not a city" aria-labelledby="label-2 error-area-2" />
    <div role="alert" class="error-area" id="error-area-2">
    <!-- insert error messages here -->
    </div> 
  </div>
  <div class="question">
    <label for="question-3" id="label-3">How old are you? <em>Note, when you leave the field, an error message should appear in a live region (polite)</em></label>
    <input type="text" id="question-3" data-error="That's no a number" aria-labelledby="label-3 error-area-3" />
    <div aria-live="polite" class="error-area" id="error-area-3">
    <!-- insert error messages here -->
    </div> 
  </div>
  <button type="button" id="button">Send in</button>
</form>
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CSS 

              
                body { font-family: sans-serif; } 
form { background: papayawhip; padding: 1em; }
label { display: block; margin: 1.5em 0 .5em; }
input, button { font-size: 100%; border: 1px solid darkgrey; padding: .5em; }
button { background-color: black; color: white; border: 0; margin: 1em 0; }
.error-area { color: darkred; font-style: italic; }
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JS 

              
                // hugely simplified, this just inserts an error 
// any time you leave any field

var fields = document.querySelectorAll( 'input' );

[].forEach.call( fields, function( field ) {
  
  field.addEventListener( 'blur', function( event ) {
      handleError( event.target );   
  });

});

               
function validate( field ) {

  // your validation magic may be more complex 
  return false;

}

function handleError( field ) {

  if ( field.getAttribute( 'data-has-error' ) !== 'true' ) {

    var error = getErrorMessage( field );
    var question = field.closest( 'div' );
    var errorArea = question.querySelector( '.error-area' );

    if ( validate( field ) === false ) {

      errorArea.appendChild( error );
      field.setAttribute( 'data-has-error', 'true' );
      
    }

  }
  
}


function getErrorMessage( field ) {
  
  var message = document.createElement( 'p' );
  var messageContent = field.getAttribute( 'data-error' );
  
  message.textContent = 'Error: ' + messageContent; 
  
  return message;

}
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999px

Console