checkit

What is checkit?

Checkit is a validation library for JavaScript that allows you to define and enforce rules for your data. It is particularly useful for validating user input in web applications.

What are checkit's main functionalities?

Basic Validation

This feature allows you to define basic validation rules for your data. In this example, the 'name' field must be present and contain only alphabetic characters, while the 'age' field must be present, an integer, and at least 18.

const Checkit = require('checkit');

const rules = new Checkit({
  name: ['required', 'alpha'],
  age: ['required', 'integer', 'min:18']
});

rules.run({ name: 'John', age: 25 })
  .then(validated => console.log('Validated:', validated))
  .catch(err => console.error('Validation failed:', err));

Custom Validation

This feature allows you to define custom validation rules. In this example, a custom rule is added to Checkit's Validator prototype, which checks if the value of 'customField' is 'customValue'.

const Checkit = require('checkit');

Checkit.Validator.prototype.customRule = function(val) {
  if (val !== 'customValue') {
    throw new Error('Value must be customValue');
  }
};

const rules = new Checkit({
  customField: ['customRule']
});

rules.run({ customField: 'customValue' })
  .then(validated => console.log('Validated:', validated))
  .catch(err => console.error('Validation failed:', err));

Asynchronous Validation

This feature allows you to define asynchronous validation rules. In this example, an asynchronous rule is added to Checkit's Validator prototype, which checks if the value of 'asyncField' is 'asyncValue' after a delay.

const Checkit = require('checkit');

Checkit.Validator.prototype.asyncRule = function(val) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      if (val === 'asyncValue') {
        resolve();
      } else {
        reject(new Error('Value must be asyncValue'));
      }
    }, 1000);
  });
};

const rules = new Checkit({
  asyncField: ['asyncRule']
});

rules.run({ asyncField: 'asyncValue' })
  .then(validated => console.log('Validated:', validated))
  .catch(err => console.error('Validation failed:', err));

Other packages similar to checkit

joi

Joi is a powerful schema description language and data validator for JavaScript. It allows you to create blueprints or schemas for JavaScript objects to ensure validation of key information. Compared to Checkit, Joi offers a more extensive set of built-in validation rules and better integration with modern JavaScript frameworks.

validator

Validator is a library of string validators and sanitizers. It is highly performant and provides a wide range of validation and sanitization functions. Unlike Checkit, which is more focused on object validation, Validator is specialized in string validation.

yup

Yup is a JavaScript schema builder for value parsing and validation. It is similar to Joi but is more lightweight and has a more modern API. Yup is often used in React applications for form validation. Compared to Checkit, Yup offers better integration with modern front-end frameworks and a more intuitive API.

README

Checkit.js

A DOM-independent validation library for Node.js and the browser.

It allows you to seamlessly validate full javascript objects, defining custom messages, labels, and validations, with full support for asynchronous validations with promises. It supports conditional validations, and has powerful, consistent error structuring and utility methods for manipulating your errors' output any way you can imagine.

var mainRules = Checkit(rules);

mainRules
  .run(obj)
  .then(function(validatedFields) {
    console.log('The fields: ' + _.keys(validatedFields).join(', ') + ' were validated!');
  })
  .caught(Checkit.Error, function(err) {
    $("#errors").html(err.map(function(val, key) {
      return '<li>' key + ': ' + val.first().message + '</li>';
    }).join(''));
  });

Installation

Checkit has three hard dependencies:

• an underscore library (lo-dash or underscore.js)
• the create-error library
• an A+ promise implementation, by default bluebird, but this may be replaced with Q or when.js.

For more reading on promises, and the Bluebird API, take a look at following links:

• Why Promises?
• Bluebird API
• Promise Anti-Patterns
• Promise Nuggets
• Snippets for Common Promise Code

Node.js

Installing with node.js npm install checkit, your dependencies should be taken care of automatically.

Browser

The easiest way to use the library is with AMD, but if you prefer to use browser globals, you'll need to include all dependencies before using the library:

<script src="/create-error.js"></script>
<script src="/lodash.js"></script> <!-- (or underscore.js) -->
<script src="/bluebird.js"></script>
<script src="/checkit.js"></script>

If you'd prefer not to use "bluebird" as the promise implementation in the browser, you should change the AMD path to a different promise library, so that Checkit.Promise is set to an object containing two methods, resolve and all.

The subsitute must be an "A+" promise implementation (jQuery won't cut it), but when.js or Q would both be suitable to swap out; if using browser globals, like the following:

Checkit.Promise = Q;

API:

Checkit(validators, [options])

The main Checkit constructor may be called with or without the new keyword, taking a hash of fields/rules for these fields to be validated.

Options:

language

Used to specify the default language key for using a particular language block.

labels

messages

Example:

var checkit = new Checkit({
  firstName: 'required',
  lastName: 'required',
  email: ['required', 'email']
});

var body = {
  email: '[e-mail]',
  firstName: 'Tim',
  lastName: 'Griesser',
  githubUsername: 'tgriesser'
};

checkit.run(body).then(function(validated) {
  console.log(validated);
}).catch(Checkit.Error, function(err) {
  console.log(err.toJSON());
})

Checkit.check(key, value, rules)

Checkit.check('email', email, ['required', 'validEmail'])
  .catch(function(err) {
    console.log(err.message)
  });

Checkit.Validators

Checkit.language

Checkit.i18n

An object containing default language

Available Validators

Validation Name	Description
accepted	The value must be yes, on, or 1. This is useful for validating "Terms of Service" acceptance.
alpha	The value must be entirely alphabetic characters.
alphaDash	The value may have alpha-numeric characters, as well as dashes and underscores.
alphaNumeric	The value must be entirely alpha-numeric characters.
alphaUnderscore	The value must be entirely alpha-numeric, with underscores but not dashes.
arguments	The value must be a javascript "arguments" object.
array	The value must be a valid array object.
base64	The value must be a base64 encoded value.
between:min:max	The value must have a size between the given min and max.
boolean	The value must be a javascript boolean.
contains:value	The value must contain the value. For a string, it does an "indexOf" check, an array "_.indexOf" and for an object "_.has".
date	The value must be a valid date object.
different:fieldName	The given field must be different than the `fieldName` under validation.
email	The field must be a valid formatted e-mail address.
empty	The value under validation must be empty; either an empty string, an empty, array, empty object, or a falsy value.
exactLength:value	The field must have the exact length of "val".
exists	The value under validation must not be undefined.
finite	The value under validation must be a finite number.
function	The value under validation must be a function.
greaterThan:value	The value under validation must be "greater than" the given value.
greaterThanEqualTo:value	The value under validation must be "greater than" or "equal to" the given value.
integer	The value must have an integer value.
ipv4	The value must be formatted as an IP address.
lessThan:value	The value must be "less than" the specified value.
lessThanEqualTo:value	The value must be "less than" or "equal to" the specified value.
luhn	The given value must pass a basic luhn (credit card) check regular expression.
matchesField:fieldName	The value must exactly match the value of another `fieldName` under validation.
max:value	The value must be less than a maximum value. Strings, numerics, and files are evaluated in the same fashion as the size rule.
maxLength:value	The value must have a length property which is less than or equal to the specified value. Note, this may be used with both arrays and strings.
min:value	The value must have a minimum value. Strings, numerics, and files are evaluated in the same fashion as the size rule.
minLength:value	The value must have a length property which is greater than or equal to the specified value. Note, this may be used with both arrays and strings.
NaN	The value must be NaN.
natural	The value must be a natural number (a number greater than or equal to 0).
naturalNonZero	The value must be a natural number, greater than or equal to 1.
null	The value must be null.
number	The value must be a javascript Number.
numeric	The value must have a numeric value.
object	The value must pass an _.isObject check.
plainObject	The value must be an object literal.
regExp	The value must be a javascript RegExp object.
required	The value must be present in the input data.
url	The value must be formatted as an URL.
uuid	Passes for a validly formatted UUID.

Conditional Validations

Sometimes you may wish to require a given field conditionally, for example require a field only if another field has a greater value than 100. Or you may need two fields to have a given value only when another field is present. Adding these validation rules doens't have to be a pain. First, create a Checkit instance with the main rules that never change:

var checkit = new Checkit({
  firstName: ['required'],
  lastName: ['required'],
  email: ['required', 'email']
});

Then use the maybe method to add additional rules:

.maybe(rules, handler)

The first of the maybe method is the hash of validation fields / settings, similar to the main Checkit object. The second argument is a function, evaluated with the object being validated, and if it returns explicitly true or with a promise fulfilling with true, it will add an additional validator to the Checkit object.

This method makes building complex conditional validations a snap.

// In this example, the "authorBio" field is only required if there are
// more than 5 books specified in the input object
checkit.maybe({authorBio: ['required', 'max:500']}, function(input) {
  return input.books > 5;
});

Advanced & Custom Validators:

First, and simplest, you can specify a function on the validation array for a property. For example:

{
  email: ['email', function(val) {
    return knex('accounts').where('email', '=', val).then(function(resp) {
      if (resp.length > 0) throw new Error('The email address is already in use.')
    })
  }]
}

You may also specify an object in one of the validator slots, specifying at the minimum a rule, and optionally params, label, and message.

{
  email: {
    rule: 'email',
    label: 'Email'
  },
  first_name: [{
    rule: 'required',
    message: 'You must supply a first name value!!'
  }, {
    rule: 'minLength:3',
    label: 'first name of this application'
  }],
  arr: {
    rule: 'contains', // different behavior than "contains:10"
    params: [10]
  }
}

Second, you may add a custom validator to the Checkit.Validators object, returning a boolean value or a promise.

Checkit.Validators.unused = function(val, table, column) {
  return knex(table).where(column, '=', val).then(function(resp) {
    if (resp.length > 0) {
      throw new Error('The ' + table + '.' + column + ' field is already in use.');
    }
  });
}

{
  email: ['email', 'unused:accounts:email']
}

Checkit Errors

One of the main features of Checkit is the error handling; By extending the error object with utility methods from underscore, the errors are even easier to work with.

• Checkit.Error
• Checkit.FieldError
• Checkit.ValidationError

Checkit.Error

The main Error object, Checkit.Error is returned from the has several helper methods & properties, as well as a number of utility methods:

.errors

The "errors" property of a Checkit.Error object is a hash of errors for each of the fields which are considered "invalid" in any way by the validation rules. The keys in this hash are the invalid fields, and the values are Checkit.FieldError objects, which in-turn have an errors attribute, an array containing errors for each failed rule.

.get(key)

The get method returns the Checkit.FieldError object for a specific key, or undefined if one does not exist.

.toString([flat])

Useful for debugging, the toString method converts the Checkit error into a human readable representation of the failed validation. If the flat argument is passed as a "truthy" value, it will output only the first ValidationError in the FieldError; otherwise it will output each validation message in a comma separated string.

.toJSON()

Converts the current error object to a json representation of the error, for easy use/refinement elsewhere. For other methods, such as map, reduce, each, see the utility methods section.

Checkit.FieldError

A FieldError is an error that contains all of the sub-errors for the validation of an individual item in the validated hash.

fieldError.errors

The errors property of a FieldError is

Checkit.ValidationErrror

A ValidationError is the result of an individual error in the field rule.

Error Utility Methods

The following methods are underscore methods proxied to the Checkit.Error and Checkit.FieldError objects, for easy manipulation of the .errors object contained in each.

shared (Checkit.Error & FieldError)

• each
• forEach
• map
• reduce
• reduceRight
• find
• filter
• reject
• invoke
• toArray
• size
• shuffle

Checkit.Error only

• keys
• values
• pairs
• invert
• pick
• omit

Checkit.FieldError only

• first
• initial
• rest
• last

Other Helpers

Checkit.labelTransform(fn)

The Checkit.labelTransform method takes a function which

Change Log

0.2.0

• CheckIt is now renamed Checkit
• Flipped the validations and target arguments, so the syntax is now Checkit(validations).run(input) rather than Checkit(input).run(validations), allowing for re-use of the validation objects.
• Tons of other internal changes, probably too many to list, pretty much a rewrite from 0.1.0

0.1.0

Initial release