Sign Up for Free

RunKit +

Try any Node.js package right in your browser

This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 400,000 packages pre-installed, including formsy-react with all npm packages installed. Try it out:

require("react/package.json"); // react is a peer dependency. require("react-dom/package.json"); // react-dom is a peer dependency. var formsyReact = require("formsy-react")

This service is provided by RunKit and is not affiliated with npm, Inc or the package authors.

formsy-react v2.0.3

A form input builder and validator for React


GitHub release Build status Coverage Status Gzipped size GitHub contributors Typescript Types included

A form input builder and validator for React.

Quick StartAPI1.x API


christianalfoni wrote an article on forms and validation with React, Nailing that validation with React JS, the result of that was this library.

The main concept is that forms, inputs, and validation are done very differently across developers and projects. This React component aims to be that “sweet spot” between flexibility and reusability.

This project was originally located at christianalfoni/formsy-react if you're looking for old issues.

What You Can Do

  1. Build any kind of form element components. Not just traditional inputs, but anything you want, and get that validation for free
  2. Add validation rules and use them with simple syntax
  3. Use handlers for different states of your form. (onSubmit, onValid, etc.)
  4. Pass external errors to the form to invalidate elements (E.g. a response from a server)
  5. Dynamically add form elements to your form and they will register/unregister to the form


yarn add formsy-react react react-dom and use with webpack, browserify, etc.

Formsy component packages

1.x to 2.x Upgrade Guide

The 2.0 release fixed a number of legacy decisions in the Formsy API, mostly a reliance on function props over value props passed down to wrapped components. However, the API changes are minor and listed below.

  • getErrorMessage() => errorMessage
  • getErrorMessages() => errorMessages
  • getValue() => value
  • hasValue() => hasValue
  • isFormDisabled(): => isFormDisabled
  • isFormSubmitted() => isFormSubmitted
  • isPristine() => isPristine
  • isRequired() => isRequired
  • isValid(): => isValid
  • showError() => showError
  • showRequired() => showRequired

Quick Start

1. Build a Formsy element

// MyInput.js
import { withFormsy } from 'formsy-react';
import React from 'react';

class MyInput extends React.Component {
  constructor(props) {
    this.changeValue = this.changeValue.bind(this);

  changeValue(event) {
    // setValue() will set the value of the component, which in
    // turn will validate it and the rest of the form
    // Important: Don't skip this step. This pattern is required
    // for Formsy to work.

  render() {
    // An error message is passed only if the component is invalid
    const errorMessage = this.props.errorMessage;

    return (
        <input onChange={this.changeValue} type="text" value={this.props.value || ''} />

export default withFormsy(MyInput);

withFormsy is a Higher-Order Component that exposes additional props to MyInput. See the API documentation to view a complete list of the props.

2. Use your Formsy element

import Formsy from 'formsy-react';
import React from 'react';
import MyInput from './MyInput';

export default class App extends React.Component {
  constructor(props) {
    this.disableButton = this.disableButton.bind(this);
    this.enableButton = this.enableButton.bind(this);
    this.state = { canSubmit: false };

  disableButton() {
    this.setState({ canSubmit: false });

  enableButton() {
    this.setState({ canSubmit: true });

  submit(model) {
    fetch('', {
      method: 'post',
      body: JSON.stringify(model),

  render() {
    return (
      <Formsy onValidSubmit={this.submit} onValid={this.enableButton} onInvalid={this.disableButton}>
        <MyInput name="email" validations="isEmail" validationError="This is not a valid email" required />
        <button type="submit" disabled={!this.state.canSubmit}>

This code results in a form with a submit button that will run the submit method when the form is submitted with a valid email. The submit button is disabled as long as the input is empty (required) and the value is not an email (isEmail). On validation error it will show the message: "This is not a valid email".


  • Fork repo
  • yarn
  • yarn lint runs lint checks
  • yarn test runs the tests
  • npm run deploy build and release formsy


Check out our Changelog and releases


The MIT License (MIT)

RunKit is a free, in-browser JavaScript dev environment for prototyping Node.js code, with every npm package installed. Sign up to share your code.
Sign Up for Free