![Logo](./.github/Logo.svg)

![Version](https://badgen.net/npm/v/formhero)
![Dependencies](https://badgen.net/david/dep/cupcakearmy/formhero)
![Size Badge](https://badgen.net/bundlephobia/minzip/formhero)

**Fully customisable react form utility.**

## 🌈 Features

- Typescript compatible
- Customizable extractor, validator, getter and setters. (More in the docs)
- **0** Dependencies
- Tiny
- React Hooks

###### Links

- [__*Live Web*__](https://cupcakearmy.github.io/formhero/)
- [__*Live React-Native*__](https://snack.expo.io/@cupcakearmy/useform)
- [Examples](#-examples)
- [Docs](#-documentation)
  - Contructor
    - [Initial State](#initial)
    - [Validators](#validators)
    - [Options](#options)
  - Returns
    - [auto](#auto)
    - [form](#form)
    - [errors](#errors)
    - [isValid](#isvalid)
    - [update](#update)
  

###### Installation

```
npm i formhero
```

## 🚀 Quickstart

```typescript
import ReactDOM from 'react-dom'
import { useForm } from 'formhero'

const Form = () => {

  const { auto, form } = useForm({
    username: '',
    password: '',
  })

  const _submit = (e: React.FormEvent) => {
    e.preventDefault()
    console.log(form)
  }

  return (
    <div>
      <form onSubmit={_submit}>
        
        <input {...auto('username')} />
        <input {...auto('password')} />

        <button type="submit">Go 🚀</button>
      </form>
    </div>
  )
}
```

## 🔥 Examples

### Validation

```typescript
const Form = () => {

  const { auto, form, errors } = useForm({
    username: '',
    email: '',
    password: ''
  }, {
    username: value => value.length > 3,
    email: {
      validator: /@/,
      message: 'Must contain an @',
    },
    password: [
      {
        validator: /[A-Z]/,
        message: 'Must contain an uppercase letter'
      },
      {
        validator: /[\d]/,
        message: 'Must contain a digit'
      },
    ]
  })

  return (
    <form>

      <h1>Errors & Validation</h1>

      <input {...auto('username')} placeholder="Username" />
      {errors.username && 'Must be longer than 3'}

      <input {...auto('email')} placeholder="EMail" />
      {errors.email}

      <input {...auto('password')} placeholder="Password" type="password" />
      {errors.password}

    </form>
  )
}
```

### Easy Customization

Often it happens that you use a specific input or framework, so the default getter, setter and extractor for the event won't cut it. No worries: formhero got you covered!

```typescript
const Form = () => {

  const { auto, form, errors } = useForm({
    awesome: true,
  })

  return (
    <form onSubmit={e => {
      e.preventDefault()
      console.log(form)
    }}>

      <h1>Custom</h1>

      <label>
        <input type="checkbox" {...auto('awesome', {
          setter: 'checked',
          getter: 'onChange',
          extractor: (e) => e.target.checked
        })} />
        Is it awesome?
          </label>

      <input type="submit" />

    </form>
  )
}
```

## 📖 Documentation

### `useForm`

```typescript
const {auto, errors, update, form, isValid} = useForm(initial, validators, options)
```

### Initial

This is the base state of the form. Also the typescript types are inhered by this.

###### Example

```javascript
const initial = {
  username: 'defaultValue',
  password: '',
  rememberMe: true,
}
```

### Validators

A validator is an object that taked in either a `RegExp` or a `Function` (can be async). Optionally you can pass a message string that will be displayed instead of the default one.

###### Example: Regular Expression

```javascript
const validators = {
  // Only contains letters. 
  // This could also be a (also async) function that returns a boolean.
  username: /^[A-z]*$/,
}
```

###### Example: Function

```typescript
const validators = {
  username: (value: string) => value.lenght > 3,
}
```

###### Example: With Object

```javascript
const validators = {
  username: {
    validator: /^[A-z]*$/,
    message: 'My custom error message',
  }
}
```

###### Example: Multiple Validators

```javascript
const validators = {
  username: [
    {
      validator: /^[A-z]*$/,
      message: 'My custom error message',
    },
    /[\d]/,
    async (value) => value.length > 0,
    {
      validator: (value) => true,
      message: 'Some other error',
    }
  ]
}
```

### Options

Sometimes it's practical to have some different default values when using for example react-native or some other framework where the default `value`, `onChange` and `(e)=> e.target.value` do not apply.

###### Example: React Native (Method 1 - Global options)

[Check the Expo Snack for a live preview](https://snack.expo.io/@cupcakearmy/useform)

```javascript
import * as React from 'react';
import { Text, SafeAreaView, TextInput } from 'react-native';
import { useForm } from 'formhero';

const initial = {
  username: 'i am all lowercase',
};
const validators = {};
const options = {
  setter: 'value', // This is not stricly necessarry as 'value' would already be the default.
  getter: 'onChangeText',
  extractor: text => text.toLowerCase(),
};

export default () => {
  const { form, auto } = useForm(initial, validators, options);

  return (
    <SafeAreaView>
      <TextInput
        style={{ height: 40, borderColor: 'gray', borderWidth: 2 }}
        {...auto('username')}
      />
      <Text>{form.username}</Text>
    </SafeAreaView>
  );
};
```

###### Example: React Native (Method 2 - Local overwrite)

```javascript
// ...

export default () => {
  const { form, auto } = useForm({
    username: 'i am all lowercase',
  });

  return (
    <SafeAreaView>
      <TextInput
        style={{ height: 40, borderColor: 'gray', borderWidth: 2 }}
        {...auto('username', {
          setter: 'value', // This is not stricly necessarry as 'value' would already be the default.
          getter: 'onChangeText',
          extractor: text => text.toLowerCase(),
        })}
      />
      <Text>{form.username}</Text>
    </SafeAreaView>
  );
};

```

### Auto

The `auto` object is used to bind the form state to the input.


###### Example: Simple

```javascript
const { auto } = useForm()

<input {...auto('username')} />
```


###### Example: With custom options

All are optional.

```javascript
const { auto } = useForm()

<input {...auto('username', {
  getter: 'onChage',
  setter: 'value',
  extractor: (e) => e.target.value
})} />
```

## Form 

This is the form state that you can use when submitting the data

###### Example 

```javascript

const { form } = useForm(...);

// ...

<form onSubmit={()=> console.log(form)}>
  // ...
</form>
```

## Errors

This object contains the error messages if a field is not valid.
The error message can be specified by you, otherwise it will return `Error in ${field}`

###### Example

```javascript
const { errors } = useForm(...)

//...

{errors.username}
{errors.password}
```

## isValid

`isValid` is a little simple helper that checks whether the `error` object is clear or if there are errors left.

## Update

The `update` function allows you to manually change and assign the state of the form. This can be usefull when you want to reset a field or the whole form. The input must have the same type as the initial state.

###### Example

```javascript
const { form, update } = useForm(...)

const resetUsername = () => {
  update({
    ...form,
    username: '',
  })
}

const resetForm = () => {
  update({
    username: '',
    password: '',
  })
}
```