react-isomorphic-form

react-isomorphic-form is a set of React components that allow you to easily create isomorphic forms in React. An isomorphic form is initially rendered on the server (with ReactDOMServer.renderToString), providing full functionality even when JavaScript is not (yet) loaded on the client. Once JavaScript is loaded, the form is enhanced to provide richer interactivity. react-isomorphic-form works well with React Router, which also supports isomorphism (e.g. its Link component does).

Don't you mean "universal"?

Yes and no. The components provided by react-isomorphic-form are universal in the sense that their source code is suitable to be executed both client- and server-side. However that is not the goal of this project. The goal is to provide a seamless transition from server-rendered HTML to client-rendered DOM without losing state, which is what we call isomorphism.

Installation

npm install --save react-isomorphic-form

How it works

Forms created with react-isomorphic-form use native HTML form behavior by default. This means they will work even without client-side JavaScript. When JavaScript is loaded, react-isomorphic-form will replace this behavior with an asynchronous request using the fetch API and send data as JSON. react-isomorphic-form also makes sure any input that was done before JavaScript kicked in is not lost, which is important especially on a slow (mobile) connection. Here's how the process works:

The server renders regular HTML form elements that will work even without client-side JavaScript.
When client-side JavaScript kicks in, react-isomorphic-form initializes its internal state, making sure any data entered thus far (while JavaScript was loading) is retained. From now on, we're dealing with controlled React components.
Form reset and submit events are handled by react-isomorphic-form. Client- side form submissions are done asynchronously.

The fetch API is not natively supported in all browsers. If the browser does not support fetch, react-isomorphic-form will fall back to a regular HTML form submission (including page transition). You can avoid this by providing a polyfill.

Example

Check out the demo app for a more elaborate example using React Router.

import { Form, Input, Label } from 'react-isomorphic-form'

<Form name="subscribe" action="/subscribe" method="post">
  <div>
    <Label name="email">Your email address:</Label>
    <Input name="email" type="email" placeholder="[email protected]" initial={email} />
  </div>
  <button type="submit">Subscribe</button>
</Form>

react-isomorphic-form provides a set of React components, each of which is a thin wrapper around a native HTML form (input) element. Any custom props provided to a component are passed on to the underlying HTML element, so you can provide your own styling and other attributes (e.g. placeholder).

We start our form with the Form component. Form requires a name, action and method and renders a <form> element with the same attributes. action should be a valid endpoint as it will be used to submit the form.

Label renders a <label> as you would expect, but you don't have to provide the htmlFor attribute. This will automatically be generated based on the name prop and the name of the containing Form. In the example above, the label will point to 'subscribe_email' and the Input will receive an id with that value.

Input renders an <input> element. As with all components, you can provide custom props and they will be passed on to the underlying HTML element. You can even provide ref and onChange and they will behave as normal. Input can also take an initial value, which will be used server-side to set the value and client-side to reset the form.

Components

There's three types of components in react-isomorphic-form: container, inputs and helpers:

Container:

Form: wrapper for <form>, maintains full state and handles submit/reset

Inputs:

Input: wrapper for <input>
Select: wrapper for <select>
Checkbox: wrapper for <input type="checkbox">
Radio: wrapper for <input type="radio">
Textarea: wrapper for <textarea>

Helpers:

Label: wrapper for <label>, binds to related input
Value: wrapper for <span>, prints current value of a field

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