form-validation-library-yr

A simple and customizable form validation library for JavaScript. It provides built-in validators for common form fields and supports custom validation logic.

Table of Contents

• Installation
• Usage
• API
  • Constructor
  • validate
  • Custom Validators
• Built-in Validators
• Examples
• Contributing
• License

Installation

Install the library using npm:

npm install form-validation-library-yr

Or using yarn:

yarn add form-validation-library-yr

Usage

First, import the library and create an instance of FormValidator with your validation rules:

import FormValidator from 'form-validation-library-yr';

const rules = {
  username: { required: true },
  email: { required: true, email: true },
  age: { required: true, integer: true },
  birthdate: { required: true, date: true, allowFuture: false },
};

const validator = new FormValidator(rules);

const formData = {
  username: 'JohnDoe',
  email: '[email protected]',
  age: '25',
  birthdate: '1995-05-15',
};

const errors = validator.validate(formData);
console.log(errors);

API

Constructor

new FormValidator(rules)

• rules (Object): An object defining the validation rules for each field.

validate

validate(formData)

• formData (Object): An object containing the form data to be validated.
• Returns: An object containing validation errors, where the keys are the field names and the values are the error messages.

Custom Validators

You can define custom validation logic by providing a custom validator function in the rules:

const rules = {
  birthdate: { 
    required: true, 
    date: true, 
    custom: { 
      validator: (value) => {
        const dateObj = new Date(value);
        const now = new Date();
        dateObj.setHours(0, 0, 0, 0);
        now.setHours(0, 0, 0, 0);
        return dateObj <= now;
      }, 
      message: 'Birthdate must be a past date'
    } 
  },
};

Built-in Validators

The library includes several built-in validators:

• required: Ensures the field is not empty.
• email: Validates an email address.
• integer: Validates that the input is an integer.
• string: Validates that the input is a string.
• date: Validates that the input is a date in the format YYYY-MM-DD.
• pattern: Validates the input against a regular expression.

Examples

Basic Usage

import FormValidator from 'form-validation-library-yr';

const rules = {
  username: { required: true },
  email: { required: true, email: true },
};

const validator = new FormValidator(rules);

const formData = {
  username: '',
  email: 'invalid-email',
};

const errors = validator.validate(formData);
console.log(errors);
// Output:
// {
//   username: 'username is required',
//   email: 'email is not a valid email address'
// }

Custom Validation

import FormValidator from 'form-validation-library-yr';

const isPastDate = (date) => {
  const dateObj = new Date(date);
  const now = new Date();
  dateObj.setHours(0, 0, 0, 0);
  now.setHours(0, 0, 0, 0);
  return dateObj <= now;
};

const rules = {
  birthdate: { 
    required: true, 
    date: true, 
    custom: { 
      validator: isPastDate, 
      message: 'Birthdate must be a past date'
    } 
  },
};

const validator = new FormValidator(rules);

const formData = {
  birthdate: '2050-01-01',
};

const errors = validator.validate(formData);
console.log(errors);
// Output:
// {
//   birthdate: 'Birthdate must be a past date'
// }

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any bugs or enhancements.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Explanation:

1. Installation: Instructions for installing the package using npm or yarn.
2. Usage: Basic example of how to use the library.
3. API: Detailed explanation of the FormValidator class methods and parameters.
4. Built-in Validators: List of built-in validators with descriptions.
5. Examples: Additional examples to demonstrate basic usage and custom validation.
6. Contributing: Information on how to contribute to the project.
7. License: License information for the project.

Below shows the gist link for example code:
Example Code Gist