netlify-cms-react-starter/src/components/NetlifyControlledForm.js

import React, { Component } from 'react'
import styled from 'styled-components'
import { stringify } from 'qs'
import { color } from '../globalStyles'
const fetch = window.fetch

class Form extends Component {
  state = {
    name: '',
    email: '',
    message: '',
    subject: `New Submission from ${this.props.siteTitle}!`,
    _gotcha: '',
    disabled: false,
    alert: '',
    action: '/contact/',
    'form-name': 'Contact'
  }

  form = null

  componentDidMount () {
    Array.from(document.querySelectorAll('.Form .Input')).forEach(input => {
      input.addEventListener('invalid', () => {
        console.log(input)
        input.dataset.touched = true
      })
      input.addEventListener('blur', () => {
        if (input.value !== '') input.dataset.touched = true
      })
    })
  }

  handleSubmit = (e) => {
    e.preventDefault()
    const data = {
      name: this.state.name,
      email: this.state.email,
      message: this.state.message,
      subject: this.state.subject,
      _gotcha: this.state._gotcha,
      'form-name': this.state['form-name']
    }
    this.setState({ disabled: true })
    fetch(this.state.action + '?' + stringify(data), {
      method: 'POST'
    })
      .then(res => {
        if (res.ok) {
          return res
        } else {
          throw new Error('Network error')
        }
      })
      .then(res => {
        this.setState({
          disabled: false,
          alert: 'Thanks for your enquiry, we will get back to you soon.',
          name: '',
          email: '',
          message: '',
          subject: `New Submission from ${this.props.siteTitle}!`,
          _gotcha: ''
        })
      })
      .catch(err => {
        console.log(err)
        this.setState({
          disabled: false,
          alert: '❗️ There is a problem, your message has not been sent, please try contacting us via email'
        })
      })
  }

  handleChange = (e) => {
    this.setState({
      [e.target.name]: e.target.value
    })
  }

  render () {
    return (
      <StyledForm
        name={this.state['form-name']}
        ref={(form) => { this.form = form }}
        className='Form'
        action={this.state.action}
        onSubmit={this.handleSubmit}
        data-netlify=''
        data-netlify-honeypot='_gotcha'
      >
        { this.state.alert && <Alert>{this.state.alert}</Alert> }
        <Label className='Label'>
          <Input value={this.state.name} onChange={this.handleChange} className='Input' type='text' placeholder='Your Name' name='name' required disabled={this.state.disabled ? 'disabled' : ''} />
          <LineGroup />
        </Label>
        <Label className='Label'>
          <Input value={this.state.email} onChange={this.handleChange} className='Input' type='email' placeholder='Your Email' name='email' required disabled={this.state.disabled ? 'disabled' : ''} />
          <LineGroup />
        </Label>
        <Label className='Label'>
          <Textarea value={this.state.message} onChange={this.handleChange} className='Input' placeholder='Message' name='message' rows='10' required disabled={this.state.disabled ? 'disabled' : ''} />
          <LineGroup />
        </Label>
        <Input type='text' name='_gotcha' style={{display: 'none'}} value={this.state._gotcha} onChange={this.handleChange} />
        <Input type='hidden' name='subject' value={this.state.subject} />
        <Input type='hidden' name='form-name' value={this.state['form-name']} />
        <Button className='button' type='submit' value='Send' disabled={this.state.disabled ? 'disabled' : ''} />
      </StyledForm>
    )
  }
}

export default Form

const LineGroup = () => (
  <Line className='Line' viewBox='0 0 40 2' preserveAspectRatio='none'>
    <path d='M0 1 L40 1' />
    <path d='M0 1 L40 1' className='focus' />
    <path d='M0 1 L40 1' className='invalid' />
    <path d='M0 1 L40 1' className='valid' />
  </Line>
)

const StyledForm = styled.form`
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  justify-content: flex-start;
  max-width: 500px;
  margin: 2.5rem 0;

  & > * + * {
    margin-top: 1.5rem;
  }
`
const Label = styled.label`
  width: 100%;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
`
const Line = styled.svg`
  width: 100%;
  height: 1px;
  stroke: #bababa;
  stroke-width: 2px;

  & .focus,
  & .valid,
  & .invalid {
    transition: all 0.2s;
    stroke-dasharray: 0, 20;
    stroke-dashoffset: -20;
  }

  & .focus {
    stroke: black;
  }

  & .valid {
    stroke: hsl(166, 72%, 40%);
  }

  & .invalid {
    stroke: var(--col1);
  }
`
const Input = styled.input`
  font-family: inherit;
  font-weight: 400;
  flex-grow: 1;
  box-sizing: border-box;
  display: block;
  margin: 0;
  border: none;
  padding: 0.5em 0;
  line-height: 1;
  transition: border-color 0.2s;
  resize: none;

  &:focus {
    outline: none;
  }

  &:focus ~ ${Line} .focus,
  &:valid ~ ${Line} .valid,
  &[data-touched]:invalid ~ ${Line} .invalid {
    stroke-dasharray: 40, 0;
    stroke-dashoffset: 0;
  }

  &[disabled]{
    opacity: .4;
    pointer-events: none;
    cursor: progress;
  }
`
const Textarea = Input.withComponent('textarea')
const Alert = styled.p`
  background: whitesmoke;
  width: 100%;
  padding: 2rem;
`
const Button = styled.input`
  background: ${color.primary};
  color: white;
  text-transform: uppercase;
  text-decoration: none;
  font-weight: 400;
  letter-spacing: .15em;
  font-size: 1.4rem;
  display: inline-block;
  padding: 1rem 2rem;
  border: none;
  transition: all .2s ease;
  cursor: pointer;

  &:hover,
  &:focus {
    color: white;
  }

  &[disabled] {
    opacity: .4;
    pointer-events: none;
    cursor: progress;
  }
`