formium

Automated progressive enhancement for <form> elements

Install

npm install formium --save

Usage

Formium is a progressive enhancement facility that allows you to seamlessly submit plain old HTML forms via AJAX and handle the response in a conventional manner.

`formium.submit(form, done?)`

Exactly as you would expect, this method will submit a <form> asynchronously via AJAX.

form.addEventListener('submit', function handler (e) {
  e.preventDefault();
  formium.submit(form, function responded (err, data) {
    // handle the response
  });
});

The form submission mechanism provided by formium will:

Run any transformers on the <form> elements before submission
Submit the <form> from within an <iframe>
- The form submission is effectively AJAX
- Browser loading indicator while the form is being posted (unlike AJAX)
- Form auto-fill values are persisted by the browser (unlike AJAX)
Run the restoration callback for each one of the previously applied transformers
Disable the <form> and <button>s inside it while the form loads
Grab the response once the <iframe> finishes loading
Call done(err, data) with this set to the form

For maximum usefulness, we recommend that you come up with some conventions to handle forms submitted via formium. For example, you could make it so responses like { redirect: '/foo' } end up redirecting the user to /foo (or rendering that view with a client-side view rendering engine). That convention alone should simplify your application so that you don't have to treat individual forms differently from one another.

`formium.configure(options)`

You can set a qs option that will be used to construct a query string appended to each AJAX form request.

formium.configure({
  qs: function (form) {
    return {
      foo: 'bar'
    };
  }
});

`formium.transform(fn)`

This method allows you to register a fn(form) callback that gets called whenever a form is submitted. You can prepare the form for submission in any way you want. You can optionally return a callback that restores the form to its original state.

The use case for Formium transforms is for those cases when you have a UX enhancement that breaks the state of the form, say if you were using insignia. In those cases, you can turn the field's value into something plain, and restore the more complex insignia tag editor right afterwards.

formium.transform(function fix (form) {
  $(form).find('.nsg-input').forEach(function (input) {
    input.attr('data-prev', input.value());
    input.value(insignia(input).value());
  });
  return function restore () {
    $(form).find('.nsg-input').forEach(function (input) {
      input.value(input.attr('data-prev'));
    });
  };
});

Events

A synthetic custom formium event is submitted on <form> DOM elements whenever we get complete a submission. It'll contain details about the response. Use this for advanced cases where you need to handle the response in a specialized way.

formium.submit(form);
form.addEventListener('formium', function (e) {
  console.log(e.detail.error);
  console.log(e.detail.data);
});

License

MIT

taunus/formium