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Unobtrusively improve forms with JavaScript. Written for ender.

Formwatcher Version 2.1.9

The formwatcher is a tool to easily improve forms with JavaScript with following goals in mind:

  • Be completely unobtrusive (your forms still work without JS)
  • Provide sensible defaults so you won't have to configure much
  • Provide the best user experience possible

It is written in CoffeeScript and built with (and depends on):

Visit the official site for a demo.


Simply install with ender:

ender build formwatcher


ender add formwatcher

You can also just download the lib/ files, and install the dependencies manually, but I don't recommend it.


The features include:

  • AJAX conversion: Turn a form into an AJAX call automatically
  • Automatically add .focus, .changed, .validated, .error, .empty, etc... classes to input fields
  • Lots of built in validators, and the possibilty to write your own
  • Decorators: Turn a simple select input field into an image selector, or a font selector or display a nice hint
  • Simple html attribute configuration that is W3C valid, either by setting classes on the input field, or using the data-fw attribute.
  • Automatching of <label> elements so you don't have to write the for="" attribute.
  • ...and more

Formwatcher is tested with qunit and works in Safari, Chrome, Firefox, Opera and IE7+.

IE7 does not have a native JSON object. So if you intend to use AJAX with your form and want to support IE7 you have to install ender-json as well.

Formwatcher modules

Those are the modules that can already exist and can be used with formwatcher:

  • formwatcher-hint Shows nice hints that fade out when the input field is focused.
  • formwatcher-date-picker Based on CalEnder
  • more coming soon...

To install any of them simply use ender like this: ender add formwatcher-hint for example.

To list all formwatcher modules in the npm registry you can simply list all modules with the formwatcher tag.


You can configure formwatcher imperatively or by defining specific html attributes on your form

Imperative configuration

Although most of the time, the simplest way to configure Formwatcher is by attribute configuration, there are a few use cases where the imperative configuration is necessary or more appropriate:'form-id');

Attribute configuration

Instead of configuring your forms with JS, you can simply add the data-fw attribute to your elements so Formwatcher knows how to handle them. The best part about it: it doesn't break your HTML markup; it still validates fine.

<form action="" data-fw="">
  <!-- Input fields -->

When Formwatcher is included, it will scan all forms in the document as soon as it's loaded to see if there is any form with the data-fw attribute, and attaches itself to it.

The data-fw attribute is just a JSON object, that will be passed to the new Watcher instance and serves as options object.

A Formwatcher configuration could look like this:

<form action="" data-fw='{ "ajax": true, "validate": false }'>

NOTE: The data-fw content is pure JSON. All names and strings have to be in double quotes, so you have to put the data-fw value itself in single quotes.

Since it's JSON, not JS, you won't be able to directly define your callback functions here.

You can directly configure decorators or validators inside this JSON object:

<form action="" data-fw='{
  "validate": true,
  "Hint": { "auto": true },
  "Float": { "decimalMark": "," }

Writing your own Validators

Adding a validator is very easy. You just push a new instance of Formwatcher.Validator to the Formwatcher.validators list.

As an example, the required validator:

# ## Required validator
# If it's a checkbox, it has to be checked. Otherwise the value can't be 0 or an empty string (whitespace is trimmed)
Formwatcher.validators.push class extends Formwatcher.Validator
  name: "Required"
  description: "Makes sure the value is not blank (nothing or spaces)."
  classNames: [ "required" ]
  validate: (value, input) ->
    return "Can not be blank." if (input.attr("type") is "checkbox" and not":checked")) or not trim value

If the validate() funciton returns a string, the validation failed, and the string is used as error message.

If true is returned, the validation passed.

Writing your own Decorators

Writing decorators is a bit more complex, but not difficult neither. The basic concept is again pushing instances of Formwatcher.Decorator to Formwatcher.decorators:

Formwatcher.decorators.push class extends Formwatcher.Decorator

  name: "SomeDecorator"
  description: "The description of the decorator"
  nodeNames: [ "INPUT", "TEXTAREA" ]
    myOption: "test"

  accepts: (input) ->
    if super input # The default implementation checks for classes and node names.
      # Return true if this decorator should decorate this input field.
      return true

  decorate: (input) ->
    # The decorate function has to return an object with all fields that have been generated and that should be updated
    # with `.focus`, `.validated`, etc... classes.
    # The `elements` object HAS TO contain at least `input` which is the field that will hold the actual value to be
    # transmitted. (It can be changed to a hidden field)
    elements = { input: input }

    # Here is your code to nicely wrap (or replace) the input field.

    return elements

Take a look at the built in hint decorator for a full example.