FORMER.JS Form Validator

Former.js is a simple, flexible, and easy-to-use form validator for javascript.

Getting started

Installation

$ npm install @devardha/former.js

Usage

former.check provides you the easy way to validate an input (string, number, boolean). former.check will return an error code (string) if the given value is invalid.

Syntax

former.check.string(input, [options]) // String validation
former.check.boolean(input) // Boolean validation
former.check.number(input) // Number/integer validation

• input

  • Type: string, boolean, or number
  • The input value you want to validate

• options (optional)

  • Type: Object
  • The options object to specify the input validation.

Options

options for string:

• type (string) - for now, only support type 'email' and 'image'
• max (number)
• min (number)
• whitespace (boolean) - Default: true

// String validation
former.check.string('this is a string') // it will return the string if valid

// Number validation
former.check.number(5)

// Boolean validation
former.check.boolean(true)

// Email validation
// To validate an email, you must specify the type
former.check.string('user@email.com', { type: 'email' })

// Image validation
former.check.string('image.jpg', { type: 'image' })

Form validation

You can also validate a form data in object using validate() method.

former.validate([formObject], [callback])

• formObject

  • Type: Object
  • The data you want to validate

• callback

  • Type: Function
  • A callback to be fired once the data has been validated.

Custom error message

former.js support custom error message for form validation using former.errorHandler().

former.errorHandler(err, [errorMessage]);

• err

  • Type: String
  • Error data

• errorMessage (optional)

  • Type: Object
  • Custom error message

Simple example

const email = former.check.string('invalidemail@email', { type: 'email' }
former.errorHandler(email, { emailError: 'Email address is invalid!' })
// => Email address is invalid!

Default error message

former.errorHandler() return the devault error message by default if you don't specify the custom error message.

• emailError: Email is invalid
• stringError: Input is not a string
• maxError: Input is too long
• minError: Input is too short
• whitespaceError: Input can't contain spaces
• numberError: Input is not a number
• booleanError: Input is not a boolean
• imageError: Invalid image or unsupported image format

Example

Simple input validation

const former = require('@devardha/former.js');

const validEmail = former.check.string('test@email.com', { type: 'email' });
console.log(validEmail)
// => test@email.com

const invalidEmail = former.check.string('invalidemail', { type: 'email' });
console.log(invalidEmail)
// => EMAIL_ERROR

Full form validation

const former = require('@devardha/former.js');

// form data must be an object
const formData = {
    email: former.check.string('test@email.com', { type: 'email' }),
    username: former.check.string('myusername', { min: 3, whitespace: false }), // the username can't contain spaces.
    password: former.check.string('secretpassword', { min: 8, max: 16 }) // password cannot have more than 16 characters
}

former.validate(formData, function (err, data) {
    if(data){
        // do something with your data here
    }

    // Handling errors
    console.log(formerjs.errorHandler(err, { minError: 'Too short bro!', whitespaceError: 'Opps, your username contain spaces' }));
})

List of former.js error code

• EMAIL_ERROR
• STRING_ERROR
• MAX_ERROR
• MIN_ERROR
• WHITESPACE_ERROR
• NUMBER_ERROR
• BOOLEAN_ERROR
• IMAGE_ERROR