This library is based on the robust validate.js. Even when validate.js will work just fine in most scenarios, sometimes you just need its core or part of it:

ES6 Modules: call specific modules in your project, only what you need.
No legacy code: don't care about jQuery and old stuff.

Install

yarn add validate-core

npm install validate-core

Basic Usage

Examples:

import { validate } from 'validate-core'

validate('email@test.com', { email: true, presence: true })
// => undefined

validate('email@test', { email: true, presence: true })
// => ["is not a valid email"]

validate('', { email: true, presence: true })
// => ["can't be blank"]

Using a specific validator

It's possible to import calling a specific validator module.

Syntax:

import <validatorName> from 'validate-core/validators/<validatorName>'

Examples:

import presence from 'validate-core/validators/presence'

presence('something') // => undefined
presence('') // => ["can't be blank"]

import date from 'validate-core/validators/email'

email('email@test.com') // => undefined
email('email@test') // => ["is not a valid email"]

API

General concepts

The `validate()` function

The library default export is a function that accepts a value as first parameter (the one you want to validate), and an object with a set of constraints as the second one:

Syntax:

import { validate } from 'validate-core'

validate(value, { ...constraints })

Example:

import { validate } from 'validate-core'

validate('email@test.com', {
  email: true,
  presence: true,
})
// => undefined

Constraints and options

The validate() function accepts as second parameter an object with the constraints (or rules) the value should match. This object should have the following syntax:

{
  validatorX:  { ...optionsForValidatorX },
  validatorY:  { ...optionsForValidatorY },
  /// ...
}

Some validators have "shortcuts" that override the constraints object with a single value.

Example with the format validator:

// With a constraint object
validate('myusername', {
  format: {
    pattern: /^@?(\w){1,15}$/,
    message: 'is not a valid Twitter account',
  },
})
// => ["is not a valid Twitter account"]

// With a shortcut
validate('myusername', {
  format: /^@?(\w){1,15}$/,
})
// => ["format is invalid"]

Note that in the shortcut version you cannot customize the error message.

Return values

validate() will return:

undefined when there is no error.
an array with one or more strings that explain what failed.

Individual validators will return almost the same output, except in some cases when they can return a string instead.

Custom `formatMessage` function

Some validators support providing a custom string formatter function using the formatMessage option.

The validators that support this are: datetime, equality, exclusion, inclusion, length, numericality and type.

The function has two parameters:

a message, with placeholders to replace.
an object with replacers: keys used to replace the placeholders with their values.

NOTE: formatMessage requires a custom message in the options.

Example for a custom message formatter for length():

import { validate } from 'validate-core'

// Using hashes for placeholders
const myCustomMesage = 'length is not exactly #is#'

// Note: length() provides the following replacers:
// - is
// - minimum
// - maximum

const myFormatter = (message = '', replacers = {}) => {
  return message.replace(/#(\w+)#/g, (match, placeholder) => {
    // console.log({ match, placeholder })
    return replacers[placeholder] || placeholder
  })
}

validate('123456', {
  length: {
    is: 5,
    message: myCustomMesage,
    formatMessage: myFormatter,
  },
})
// => ["length is not exactly 5"]

Validators

`date`

The date validator is just a shorthand for the datetime validator with the dateOnly option set to true.

Examples:

import { validate } from 'validate-core'

validate(new Date('2010-10-01'), {
  date: true,
})
// => undefined

validate(new Date('2010-10-01 12:34:56'), {
  date: true,
})
// => ["must be a date (not a datetime)"]

`datetime`

This validator can be used to validate dates and times. Since date parsing in javascript is very poor, some additional work is required to make this work.

Before this validator can be used, the parse and format functions need to be set. The parse function should take the value to parse (non null but otherwise untouched) and return the unix timestamp (in milliseconds) for that date or NaN if it's invalid.

It's important to mention that the constraints (laterThan, earlierThan) will also be parsed using this method. These arguments will be parsed using the parse function, just like the value.

The format function should take a unix timestamp (in milliseconds) and format it in a user friendly way.

You can specify the follow constraints:

laterThan: The date cannot be before this time.
earlierThan: The date cannot be after this time.
dateOnly: If true, only dates (not datetimes) will be allowed. Default: false.

You can change the messages by setting any of these settings the options for the validator:

notValid (default: must be a valid date).
dateOnlyMessage: (default: must be a date (not a datetime)).
tooEarly (default: must be later than %{date}).
tooLate (default: must be earlier than %{date}).

You can use the placeholders %{value} and %{date} in the messages.

Examples:

import { validate } from 'validate-core'

validate(new Date('2010-10-01 12:34:56'), {
  datetime: true,
})
// => undefined

validate(new Date('2010-10-01'), {
  datetime: {
    dateOnly: true,
  },
})
// => undefined

validate(new Date('2010-09-15'), {
  datetime: {
    laterThan: new Date('2010-10-01'),
    tooEarly: 'choose a date after %{date}',
    earlierThan: new Date('2010-10-31'),
    tooLate: 'choose a date before %{date}',
  },
})
// => ["choose a date after 2010-10-01"]

`email`

The email validator attempts to make sure that the input is a valid email. Validating emails is tricky business due to the complex rules of email address formatting.

For example john.doe@gmail is a perfectly valid email but it's most likely just the case that John has forgotten to write .com at the end.

validate-core (as is based on validate.js) tries to be pragmatic and allows most valid emails, but tries to catch common typos such as forgetting the TLD.

If you want to know more about email validation the Wikipedia article and the email page on regular-expressions.info are good places to start.

You can customize the regexp used by setting the pattern option to a regexp of your choosing. Just remember that javascript regexp does substring matching.

The default message is is not a valid email and as usual you can override it using the message option.

Examples:

import { validate } from 'validate-core'

validate('nice@email.com', { email: true })
// => undefined

validate('bad@email', { email: true })
// => ["is not a valid email"]

validate('bad@email', { email: { message: 'wrong e-mail format' } })
// => ["wrong e-mail format"]

`equality`

The equality validator can be used to verify that one attribute is always equal to another.

This is useful when having a "confirm password" input, for example.

You specify which attribute by simply passing its value as the options for the validator or by giving the option attribute with the value inside.

By default === is used to check the quality, it you need to validate more complex objects you can give a function using the comparator option which should be a function that accepts two arguments and returns true if they objects are equal and false if they are not.

The default message is is not equal to %{attribute}

Examples:

import { validate } from 'validate-core'

validate(123, { equals: 123 })
// => undefined

validate('foo', { equals: { attribute: 'foo' } })
// => undefined

validate('foo', { equals: 'bar' })
// => ["is not equal to bar"]

`format`

The format validator will check a value against a regular expression of your choosing. The default message if the value doesn't match is is invalid so you'll likely want to customize it by setting message to something in the options.

The pattern option can either be a javascript regexp or string that will be passed to the RegExp constructor. If the pattern is a string and you want to specify flags, you may use the flags option.

Please note that the whole string must match the regexp, not just a part of the value.

Examples:

import { validate } from 'validate-core'

validate('(123) 456-7890', {
  format: /^\D?(\d{3})\D?\D?(\d{3})\D?(\d{4})$/, // US Phone format
})
// => undefined

validate('(123) 456-7890', {
  format: {
    pattern: '^D?(d{3})D?D?(d{3})D?(d{4})$', // US Phone format
  },
})
// => undefined

`exclusion`

The exclusion validator is useful for restriction of certain values.

It checks that the given value is not in the list given by the within option.

You can specify within as a list or as an object (in which case the keys of the object are used).

The default message is %{value} is restricted and can be changed by setting the message option.

Examples:

import { validate } from 'validate-core'

validate('baz', { exclusion: { within: ['foo', 'bar'] } })
// => undefined

validate('foo', { exclusion: { within: ['foo', 'bar'] } })
// => ["foo is restricted"]

`inclusion`

The inclusion validator is useful for validating input from a dropdown, for example.

It checks that the given value exists in the list given by the within option.

You can specify within as a list or as an object (in which case the keys of the object are used).

The default message is %{value} is not included in the list and can be changed by setting the message option.

Examples:

import { validate } from 'validate-core'

validate('foo', {
  inclusion: {
    within: ['foo', 'bar']
  }
})
// => undefined

validate('baz', {
  inclusion: {
    within: ['foo', 'bar']
  }
})
// => ["foo is not included in the list"]

validate('baz', {
  inclusion: {
    within: ['foo', 'bar'],
    message: {'%{value} is not allowed'} }
})
// => ["foo is not allowed"]

`length`

The length validator will check the length of a string.

Any object with the length property can be validated, but all the default error messages refer to strings, so make sure you override them if you plan on validating arrays using this.

You may specify the following length constraints:

is: The value has to have exactly this length.
minimum: The value cannot be shorter than this value.
maximum: The value cannot be longer than this value.

You can specify the error message using the notValid, wrongLength, tooShort and tooLong options:

notValid (default: has an incorrect length).
tooLong (default: is too long (maximum is %{count} characters)).
tooShort (default: is too short (minimum is %{count} characters)).
wrongLength (default: is the wrong length (should be %{count} characters)).

As you may have noticed you can use %{count} as a placeholder for the actual constraint and it will be replaced for you.

You can also use the message option as the message for all errors (this overrides any other custom errors).

By default the number of characters are counted (using the length property). If you want to count something else, you can specify the tokenizer option, which should be a function that takes a single argument (the value) and returns a value that should be used when counting.

The tokenizer will not be called with nil or undefined as an argument.

One important thing to note is that the value for the length property has to be a number; otherwise the message has an incorrect length is returned.

An error is also logged to the console, since this is considered a coding error.

Examples:

import { validate } from 'validate-core'

validate('12345', { length: { is: 5 } })
// => undefined

validate('12345', { length: { minimum: 6 } })
// => ["is too short (minimum is 6 characters)"]

validate('12345', { length: { maximum: 4 } })
// => ["is too long (maximum is 4 characters)"]

`numericality`

The numericality validator will only allow numbers. By default strings are coerced to numbers using the + operator. If this is not desirable, you can set the noStrings option to true to disable this behaviour.

The following constraints can be applied:

strict: Enables more strict validation of strings. Leading zeroes won't be allowed and the number cannot be malformed.
onlyInteger: Real numbers won't be allowed.
greaterThan: The input has to be greater than this value.
greaterThanOrEqualTo: The input has to be at least this value.
equalTo: The input has to be exactly this value.
lessThanOrEqualTo: The input can be this value at the most
lessThan: The input has to be less than this value.
divisibleBy: The input has to be divisible by this value.
odd: The input has to be odd.
even: The input has to be even.

If you want a custom error message, you may specify it using the message option or by specifying one of the following messages:

notValid (default: must be a valid number).
notInteger (default: must be an integer).
notGreaterThan (default: must be greater than %{count}).
notGreaterThanOrEqualTo (default: must be greater than or equal to %{count}).
notEqualTo (default: must be equal to %{count}).
notLessThan (default: must be less than %{count}).
notLessThanOrEqualTo (default: must be less than or equal to %{count}).
notDivisibleBy (default: must be divisible by %{count}).
notOdd (default: must be odd).
notEven (default: must be even).

Examples:

import { validate } from 'validate-core'

validate(123.4, {
  numericality: true,
})
// => undefined

validate('-123.4', {
  numericality: true,
})
// => undefined

validate(24, {
  numericality: {
    divisibleBy: 5,
  },
})
// => ["must be divisible by 5"]

validate(80, {
  numericality: {
    greaterThan: 100,
    notGreaterThan: 'please enter a number greater than %{count}',
  },
})
// => ["please enter a number greater than 100"]

`presence`

The presence validator checks that the value is defined. This validator will probably be the most used one, it corresponds to HTML5's required attribute.

You can use the message option to customize the message. The default message is can't be blank.

These are the values that are considered empty:

null
undefined

Additionally you can set the allowEmpty to true to allow the following values:

{} (empty objects).
[] (empty arrays).
"" (empty string).
" " (whitespace only string).

Important! All other values are considered valid (including functions)!

Examples:

import { validate } from 'validate-core'

validate('something', { presence: true })
// => undefined

validate('', { presence: true })
// => ["can't be blank"]

validate(null, { presence: true })
// => ["can't be blank"]

validate('', { presence: { allowEmpty: true } })
// => undefined

validate('', { presence: { message: 'is required' } })
// => ["is required"]

`url`

The URL validator ensures that the input is a valid URL. Validating URLs is pretty tricky, but this validator follows a gist that can be found here.

The following options are supported:

message: The message if the validator fails. Defaults to is not a valid url.
schemes: A list of schemes to allow. If you want to support any scheme you can use a regexp here (for example [".+"]). The default value is: ["http", "https"].
allowLocal: A boolean that if true allows local hostnames such as 10.0.1.1 or localhost. The default is false.

Examples:

import { validate } from 'validate-core'

validate('https://google.com', { url: true })
// => undefined

validate('google.com', { url: true }) // missing scheme!
// => ["is not a valid url"]

Utility methods

TODO: Add Utilities API here!

Development

Dev mode

# yarn
yarn dev

# or npm
npm run dev

Build

# yarn
yarn build

# or npm
npm run build

Run Tests

Tests are written with jest

# yarn
yarn test
yarn test:watch # watch mode

# or npm
npm run test
npm run test:watch # watch mode

Acknowledges

This project was forked initialy from Nicklas Ansman's validate.js

License

The MIT License (MIT)

(Read more in LICENSE file)

Keywords

FAQs

What is validate-core?

Is validate-core popular?

Is validate-core well maintained?

Last updated on 01 Oct 2020

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Install

validate-core

validate-core

Features

Yet another validation library? Why?

Install

Basic Usage

Using a specific validator

API

General concepts

The validate() function

Constraints and options

Return values

Custom formatMessage function

Validators

date

datetime

email

equality

format

exclusion

inclusion

length

numericality

presence

url

Utility methods

Development

Dev mode

Build

Run Tests

Acknowledges

License

Keywords

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The `validate()` function

Custom `formatMessage` function

`date`

`datetime`

`email`

`equality`

`format`

`exclusion`

`inclusion`

`length`

`numericality`

`presence`

`url`