use-form-input

USE-FORM-INPUT

Simple hook to provide form validation in react

Features

• Small size and no dependencies
• Easy to use APIs
• Fully customizable form handling and validations

Installation

Install:

npm i use-form-input

Quickstart

1. Basic form handling

Form handling can be done with useFormInput.

Example:

// Basic form handling
import { useFormInput } from 'use-form-input';

export default function BasicFormHandling() {
  const [data, { onChange, onSubmit }] = useFormInput(
    {
      firstName: '',
      lastName: '',
    },
    (data) => {
      console.log('FINAL DATA', data);
    }
  );

  return (
    <>
      <form onSubmit={onSubmit} style={{ marginLeft: 10 }}>
        <input
          type="text"
          name="firstName"
          value={data.firstName}
          onChange={onChange}
        />
        <br />

        <input
          type="text"
          name="lastName"
          value={data.lastName}
          onChange={onChange}
        />
        <br />

        <input value="Submit" type="submit" />
      </form>
    </>
  );
}

Note: The form element must have name prop available to use onChange.

2. Form Validation

Form validation can be done by passing third parameter ( function ) which should return an error object. The function is called with the data.

Example:

import { useFormInput } from 'use-form-input';

export default function FormValidation() {
  const [data, { onChange, onSubmit, errors, modified }] = useFormInput(
    {
      firstName: '',
      lastName: '',
    },
    (data) => {
      console.log('FINAL DATA', data);
    },
    (data) => {
      const errors = {};

      if (data.firstName.length === 0) {
        errors.firstName = 'Empty first name';
      }

      if (data.lastName.length === 0) {
        errors.lastName = 'Empty last name';
      }

      return errors;
    }
  );

  return (
    <>
      <form onSubmit={onSubmit} style={{ marginLeft: 10 }}>
        <input
          type="text"
          name="firstName"
          value={data.firstName}
          onChange={onChange}
        />
        {modified.firstName && errors.firstName && (
          <span style={{ color: 'red' }}>{errors.firstName}</span>
        )}
        <br />

        <input
          type="text"
          name="lastName"
          value={data.lastName}
          onChange={onChange}
        />
        {modified.lastName && errors.lastName && (
          <span style={{ color: 'red' }}>{errors.lastName}</span>
        )}
        <br />

        <input value="Submit" type="submit" />
      </form>
    </>
  );
}

Note: modified object is used so that, the error is not shown by default. The form should either be submitted or certain fields must change before it should show error. modified object has the property same as fields passed to useFormInput hook.

3. Manual Validation

Form can be manually validated by using validator, setErrors and isValid methods.

Example:

import { useFormInput } from 'use-form-input';

export default function ManualValidation() {
  const [data, { onChange, errors, setErrors, isValid, validator }] =
    useFormInput({
      firstName: '',
      lastName: '',
    });

  const onSubmit = (e) => {
    e.preventDefault();

    const catchedErrors = {};
    const validate = validator(catchedErrors);

    validate('firstName', {
      condition: data.firstName.length === 0,
      message: 'Empty first name',
    });

    validate('lastName', {
      condition: data.lastName.length === 0,
      message: 'Emptry last name',
    });

    setErrors(catchedErrors);

    if (!isValid(catchedErrors)) {
      return;
    }

    console.log('FINAL DATA', data);
  };

  return (
    <>
      <form onSubmit={onSubmit} style={{ marginLeft: 10 }}>
        <input
          type="text"
          name="firstName"
          value={data.firstName}
          onChange={onChange}
        />
        {errors.firstName && (
          <span style={{ color: 'red' }}>{errors.firstName}</span>
        )}
        <br />

        <input
          type="text"
          name="lastName"
          value={data.lastName}
          onChange={onChange}
        />
        {errors.lastName && (
          <span style={{ color: 'red' }}>{errors.lastName}</span>
        )}
        <br />

        <input value="Submit" type="submit" />
      </form>
    </>
  );
}

4. Manually Setting Values

We need a method to manually set the values of certain fields. We can do it by using setValue method.

Example:

const [data, { setValue }] = useFormInput({ firstName: '' });

...

<input
  type="text"
  name="firstName"
  value={data.firstName}
  onChange={e => setValue('firstName', e.target.value)}
/>

setValue accepts two parameters:

• Field Name
• Value

5. Modifiying previous values

We can modify the previous values using setValue method. For example, we can use it in checkbox.

Example:

const [data, { setValue }] = useFormInput({ married: false });

...

<input
  type="text"
  name="married"
  checked={data.married}
  onChange={e => setValue('married', (previousValue) => !previousValue)}
/>

It works like a setState function, getting previous value and returning modified one.

6. Clearing form

We can clear the from by using clear method which sets all the modified fields to its initial one.

Example:

const [data, { clear }] = useFormInput({ firstName: '', lastName: '' });

...

<button onClick={() => clear()}>Clear</button>

License

MIT