A constructor function for data validation on both the server and client, inspired by the Laravel PHP framework's Validator class.

npm install validatorjs
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validatorjs v1.0.1

Build Status

The validatorjs library makes data validation in JavaScript very easy on both the client and server side (Node.js). This library was inspired by the Laravel framework's Validator class so you will see a lot of similarities in the library's API.

1.0.0 Changes

  • In versions < 1.0.0, most validation rules had an implicit 'required' rule. For example, if I specified that a field had the 'email' validation flag, it would fail if an empty string was passed. This made it difficult to have optional fields with required formats. In v1.0.0, the validation rules do not have an implicit 'required'. If a field is undefined or an empty string, it will pass validation. If you want a validation to fail for undefined or '', use the required rule.
  • validation_instance.first() has been removed. Use validation_instance.errors.first() instead



  1. Include validator.min.js script onto your page from the distribution folder dist.
  2. Invoke the Validator constructor function. See below for details on Validator parameters and validation rules.


Install the Validator package from the NPM registry

npm install validatorjs
var Validator = require('validatorjs');

Usage and Examples

The 1st argument to the constructor is an object that contains the data you want to validate.

The 2nd argument is an object that contains the validation rules.

The 3rd argument is an optional object that can contain custom error messages to return.

Example 1:

    var data = {
        name: 'David',
        email: '',
        age: 28

    var rules = {
        name: 'required',
        email: 'required|email',
        age: 'min:18'

    var validation = new Validator(data, rules);

    validation.passes() // true
    validation.fails() // false

To apply validation rules to the data object, use the same object key names for the rules object.

Example 2:

    var validation = new Validator({
        name: 'D',
        email: 'not an email'
    }, {
        name: 'size:3',
        email: 'required|email'

    validation.fails(); // true
    validation.passes(); // false

    // Error messages
    validation.errors.first('email'); // 'The email format is invalid.'
    validation.errors.get('email'); // returns an array of all email error messages

Validation Rules

Note: Input values of undefined or an empty string '' will pass as true. Use the required flag if they should fail validation.


The field under validation must be yes, on, or 1. This is useful for validating "Terms of Service" acceptance.


The field under validation must be entirely alphabetic characters.


The field under validation may have alpha-numeric characters, as well as dashes and underscores.


The field under validation must be entirely alpha-numeric characters.


The field under validation must have a matching field of foo_confirmation. For example, if the field under validation is password, a matching password_confirmation field must be present in the input.


The given field must be different than the field under validation.


The field under validation must be formatted as an e-mail address.

    address: 'email'


The field under validation must be included in the given list of values.


The field under validation must have an integer value.


Validate that an attribute is no greater than a given size

    cost: 'max:100'

Note: Maximum checks are inclusive.


Validate that an attribute is at least a given size.

    payment: 'min:10'

Note: Minimum checks are inclusive.


The field under validation must not be included in the given list of values.


Validate that an attribute is numeric. The string representation of a number will pass.

    age: 'numeric'


Checks if the length of the String representation of the value is >

    username: 'required'


The given field must match the field under validation.


Validate that an attribute is a given length, or, if an attribute is numeric, is a given value

    duration: 'size:2'


Validate that an attribute has a valid URL format

    link: 'url'

Register a custom validation rule

    Validator.register(custom_rule_name, callbackFn, errorMessage);
  • custom_rule_name - string
  • callbackFn - function. If callbackFn returns a truthy value, the validation will pass for this rule. Otherwise, this validation rule will fail.
  • errorMessage is an optional string where you can specify a custom error message. :attribute inside errorMessage will be replaced with the attribute name.
    Validator.register('telephone', function(value, requirement, attribute) { // requirement paramter defaults to null
        return val.match(/^\d{3}-\d{3}-\d{4}$/);
    }, 'The :attribute phone number is not in the format XXX-XXX-XXXX.');

Error Messages

This contructor will automatically generate error messages for validation rules that failed.

If there are errors, the Validator instance will have its errors property object populated with the error messages for all failing attributes. The methods and properties on the errors property object are:


returns the first error message for an attribute, false otherwise


returns an array of error messages for an attribute, or an empty array if there are no errors


the number of validation errors


    var validation = new Validator(input, rules);
    validation.errors.first('email'); // returns first error message for email attribute
    validator.errors.get('email'); // returns an array of error messages for the email attribute

Custom Error Messages

If you need a specific error message and you don't want to override the default one, you can pass an override as the third argument to the Validator object, just like with Laravel.

    var input = {
        name: ''
    var rules = {
        name : 'required'
    var validation = new Validator(input, rules, {required: 'You forgot to give a :attribute'});
    validation.errors.first('name'); // returns 'You forgot to give a name'

Some of the validators have string and numeric versions. You can change them too.

    var input = {
        username: 'myusernameistolong'
    var rules = {
        username : 'max:16'
    var validation = new Validator(input, rules, {max: {string: 'The :attribute is too long. Max length is :max.'}});
    validation.errors.first('username'); // returns 'The username is too long. Max length is 16.'

You can even provide error messages on a per attribute basis! Just set the message's key to 'validator.attribute'

    var input = {
        name: '',
        email: ''
    var rules = {
        name : 'required',
        email : 'required'
    var validation = new Validator(input, rules, {'': 'Without an :attribute we can\'t reach you!'});
    validation.errors.first('name'); // returns  'The name field is required.'
    validation.errors.first('email'); // returns 'Without an email we can\'t reach you!'

Public Instance Methods


returns boolean


returns boolean


Install node module dependencies

npm install

See SpecRunner.html for Jasmine tests in the browser.

You can also run the jasmine tests via Node.js once you've installed the NPM package jasmine-node.

jasmine-node spec/ --verbose --color
npm test (which calls the above command)

Once the above test passes, run the following command which will in turn run JSHint and minify the source



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