JS Form Validator

JS Form Validator is a simple form data validation library for JavaScript. It provides a set of base rules for checking the type and value of various inputs, and allows you to define custom rules as well.

Installation

To install JS Form Validator, use one of the following package managers:

npm install --save js-formdata-validator

pnpm add js-formdata-validator

Nuxt 2 Installation

// nuxt.config.js
// Add transpile
build: {
	transpile: [/js-formdata-validator/],
},

Usage

To use JS Form Validator, import the Validator class and create a new instance, passing in an object with the following properties:

formData: An object containing the form data to be validated.
rules: An object specifying the validation rules for each field in the form data. (rules is not required to be pass as an parameter here) Here's an example of how to use JS Form Validator to validate a form with a required name field:

import { Validator } from "js-formdata-validator";

const formData = {
    name: null,
    deep: {
        neested: {
            object: {
                value: null
            }
        }
    },
    arrayObject: [
        {
            objectName: "object a name"
        },
        {
            objectName: null
        },
        {
            objectName: "object c name"
        },
    ]
};
const validator = new Validator({
  formData: formData,
  rules: {
    name: ["required"],
    "deep.nested.object.value": ["required"],
    "arrayObject.*.objectName": ["required"]
  },
});

// Validate the form data
await validator.validate();

// Check if the validation failed
if (validator.fail()) {
  // Get the validation error messages
  const error = validator.getErrorBag();
  console.log(error); // Output: {name: ["The field is required."], "deep.nested.object.value": ["The field is required."], "arrayObject.1.objectName": ["The field is required."]}
}

Base Rules

JS Form Validator provides the following base rules for validating form data:

Validation Type	Description
required	Checks if the value is undefined, an empty string, or null.
array	Checks if the value is an instance of the Array class.
integer	Checks if the value is an integer using the Number.isInteger() method.
numeric	Checks if the value is an instance of the Number class.
string	Checks if the value is a string.
boolean	Checks if the value is a boolean.
allowed	Checks if the value is included in a list of allowed values passed as arguments to the function.
image	Checks if the value is an instance of the File class, and also checks if the file's MIME type starts with "image/".
size	Checks if the value is an instance of the File class, and also checks if the file's size is within a specified range.
email	Checks if the value is an email value.
min	Checks if the value is more than min value.
max	Checks if the value is below the max value.
accepted	Checks if the value is accepted ("yes", "on", 1, true).
between	Checks if the value is between 2 arg (between:1,3).
declined	Checks if the value is declined ("no", "off", 0, false).
ipv4	Checks if the value is ipv4.
ipv6	Checks if the value is ipv6.
date	Checks if the value type is date.

Extends Custom Rules

JS Form Validator provides extendable custom rule to be runs alongside base rules, heres the code example:

const formData = {
    age: 25,
};
const validator = new Validator({
    formData: formData,
    rules: {
        age: ["custom"],
    },
}).mergeCustomRules({
    custom(value) {
        if (value === 25) {
            return "Test Error";
        }
    },
});

// Validate the form data
await validator.validate();

// Check if the validation failed
if (validator.fail()) {
  // Get the validation error messages
  const error = validator.getErrorBag();
  console.log(error);
}

Function parameters

We can also parse parameters to the custom rules

const formData = {
  age: 25
};
const validator = new Validator({
  formData: formData,
  rules: {
    age: ["ageBetween:26,50"]
  },
})
validator.mergeCustomRules({
    ageBetween(value, paramA, paramB) {
        // paramA will be 26
        // paramB will be 50
        if (value < paramA || value > paramB) {
            return `Age must be between ${paramA} - ${paramB}`;
        }
    },
});

Anonymous Function

Or set anonymous function inside the array rules

const formData = {
  age: 25
};
const validator = new Validator({
  formData: formData,
  rules: {
    age: [
        (value) {
            const min = 26
            const max = 50
            if (value < min || value > max) {
                return `Age must be between ${min} - ${max}`;
            }
        }
    ]
  },
})

Async / Await syntax

It can also use async / await syntax to fetch data and wait it to be fetched from some external source

const formData = {
  age: 25
};
const validator = new Validator({
  formData: formData,
  rules: {
    age: [
        async (value) {
            const response = await fetch('/path/to/your/api');
						const { min, max } = response.json();
						
            if (value < min || value > max) {
                return `Age must be between ${min} - ${max}`;
            }
        }
    ]
  },
})

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