var syncModel = require('sync-model');
var model = require('model');
var el,
    entity,
    EntityClass;
el = document.querySelector('#my-form');
EntityClass = model(...)
  .use(
    syncModel({
      date: function(value) {
        return new Date(value);
      }
    })
  )
  .attr('my-attr', { type: 'string', format: 'date' });
entity = new EntityClass(...);
entity.syncWith(el);

function myHandler(value) {
  // convert value to a representation
  return convert(value);
}

{
  '<format-name>': function(value) {},
  ...
}