aeLe7aes.js

function validate(fields) {
  return {
    username: [{
      type: 'contains_invalid_chars',
      payload: {
        badChars: '@'
      }
    }, {
      type: 'some_other_error'.
      payload: {
        // ...
      }
    }]
  };
}



<input name="username">
{# username }
  {# type === 'contan' }
    Bad because <strong>{{badChars}}</strong>
  {/}
{/username}