fastest-validator (2024)

⚡ The fastest JS validator library for NodeJS | Browser | Deno.

Key features

blazing fast! Really!
20+ built-in validators
many sanitizations
custom validators & aliases
nested objects & array handling
strict object validation
multiple validators
customizable error messages
programmable error object
no dependencies
unit tests & 100% coverage

How fast?

Very fast! 8 million validations/sec (on Intel i7-4770K, Node.JS: 12.14.1)

√ validate 8,678,752 rps

Compared to other popular libraries:

50x faster than Joi.

Would you like to test it?

$ git clone https://github.com/icebob/fastest-validator.git$ cd fastest-validator$ npm install$ npm run bench

Approach

In order to achieve lowest cost/highest performance redaction fastest-validator creates and compiles functions using the Function constructor. It's important to distinguish this from the dangers of a runtime eval, no user input is involved in creating the validation schema that compiles into the function. This is as safe as writing code normally and having it compiled by V8 in the usual way.

NPM

You can install it via NPM.

$ npm i fastest-validator --save

$ yarn add fastest-validator

Validate

The first step is to compile the schema to a compiled "checker" function. After that, to validate your object, just call this "checker" function.

This method is the fastest.

const Validator = require("fastest-validator");const v = new Validator();const schema = { id: { type: "number", positive: true, integer: true }, name: { type: "string", min: 3, max: 255 }, status: "boolean" // short-hand def};const check = v.compile(schema);console.log("First:", check({ id: 5, name: "John", status: true }));// Returns: trueconsole.log("Second:", check({ id: 2, name: "Adam" }));/* Returns an array with errors: [ { type: 'required', field: 'status', message: 'The \'status\' field is required!' } ]*/

Try it on Repl.it

Halting

If you want to halt immediately after the first error:

const v = new Validator({ haltOnFirstError: true });

Browser usage

<script src="https://unpkg.com/fastest-validator"></script>

const v = new FastestValidator();const schema = { id: { type: "number", positive: true, integer: true }, name: { type: "string", min: 3, max: 255 }, status: "boolean" // short-hand def};const check = v.compile(schema);console.log(check({ id: 5, name: "John", status: true }));// Returns: true

Deno usage

With esm.sh, now Typescript is supported

import FastestValidator from "https://esm.sh/fastest-validator@1"const v = new FastestValidator();const check = v.compile({ name: "string", age: "number",});console.log(check({ name: "Erf", age: 18 })); //true

Supported frameworks

Moleculer: Natively supported
Fastify: By using fastify-fv
Express: By using fastest-express-validator

Optional

Every field in the schema will be required by default. If you'd like to define optional fields, set optional: true.

const schema = { name: { type: "string" }, // required age: { type: "number", optional: true }}const check = v.compile(schema);check({ name: "John", age: 42 }); // Validcheck({ name: "John" }); // Validcheck({ age: 42 }); // Fail because name is required

Nullable

If you want disallow undefined value but allow null value, use nullable instead of optional.

const schema = { age: { type: "number", nullable: true }}const check = v.compile(schema);check({ age: 42 }); // Validcheck({ age: null }); // Validcheck({ age: undefined }); // Fail because undefined is disallowedcheck({}); // Fail because undefined is disallowed

Nullable and default values

null is a valid input for nullable fields that has default value.

const schema = { about: { type: "string", nullable: true, default: "Hi! I'm using javascript" }}const check = v.compile(schema)const object1 = { about: undefined }check(object1) // Validobject1.about // is "Hi! I'm using javascript"const object2 = { about: null }check(object2) // validobject2.about // is nullcheck({ about: "Custom" }) // Valid

Considering `null` as a value

In specific case, you may want to consider null as a valid input even for a required field.

It's useful in cases you want a field to be:

required and null without specifying nullable: true in its definition.
required and not null by specifying nullable: false in its definition.
optional but specifically not null.

To be able to achieve this you'll have to set the considerNullAsAValue validator option to true.

const v = new Validator({considerNullAsAValue: true});const schema = {foo: {type: "number"}, bar: {type: "number", optional: true, nullable: false}, baz: {type: "number", nullable: false}};const check = v.compile(schema);const object1 = {foo: null, baz: 1};check(object1); // valid (foo is required and can be null)const object2 = {foo: 3, bar: null, baz: 1};check(object2); // not valid (bar is optional but can't be null)const object3 = {foo: 3, baz: null};check(object3); // not valid (baz is required but can't be null)

With this option set all fields will be considered nullable by default.

Object properties which are not specified on the schema are ignored by default. If you set the $$strict option to true any additional properties will result in an strictObject error.

const schema = { name: { type: "string" }, // required $$strict: true // no additional properties allowed}const check = v.compile(schema);check({ name: "John" }); // Validcheck({ name: "John", age: 42 }); // Fail

Remove additional fields

To remove the additional fields in the object, set $$strict: "remove".

It is possible to define more validators for a field. In this case, only one validator needs to succeed for the field to be valid.

const schema = { cache: [ { type: "string" }, { type: "boolean" } ]}const check = v.compile(schema);check({ cache: true }); // Validcheck({ cache: "redis://" }); // Validcheck({ cache: 150 }); // Fail

Basically the validator expects that you want to validate a Javascript object. If you want others, you can define the root level schema, as well. In this case set the $$root: true property.

Example to validate a string variable instead of object

const schema = { $$root: true, type: "string", min: 3, max: 6};const check = v.compile(schema);check("John"); // Validcheck("Al"); // Fail, too short.

The library contains several sanitizers. Please note, the sanitizers change the original checked object.

Default values

Array of X

const schema = { foo: "string[]" // means array of string}const check = v.compile(schema);check({ foo: ["bar"] }) // true

Nested objects

const schema = { dot: { $$type: "object", x: "number", // object props here y: "number", // object props here }, circle: { $$type: "object|optional", // using other shorthands o: { $$type: "object", x: "number", y: "number", }, r: "number" }};

You can define custom aliases.

v.alias('username', { type: 'string', min: 4, max: 30 // ...});const schema = { username: "username|max:100", // Using the 'username' alias password: "string|min:6",}

You can set default rule options.

const v = new FastestValidator({ defaults: { object: { strict: "remove" } }});

You can use label names in error messages instead of property names.

const schema = {email: { type: "email", label: "Email Address" },};const check = v.compile(schema);console.log(check({ email: "notAnEmail" }));/* Returns[ { type: 'email', message: "The 'Email Address' field must be a valid e-mail.", field: 'email', actual: 'notAnEmail', label: 'Email Address' }]*/

`any`

This does not do type validation. Accepts any types.

const schema = { prop: { type: "any" }}const check = v.compile(schema)check({ prop: true }); // Validcheck({ prop: 100 }); // Validcheck({ prop: "John" }); // Valid

`array`

This is an Array validator.

Simple example with strings:

const schema = { roles: { type: "array", items: "string" }}const check = v.compile(schema)check({ roles: ["user"] }); // Validcheck({ roles: [] }); // Validcheck({ roles: "user" }); // Fail

Example with only positive numbers:

const schema = { list: { type: "array", min: 2, items: { type: "number", positive: true, integer: true } }}const check = v.compile(schema)check({ list: [2, 4] }); // Validcheck({ list: [1, 5, 8] }); // Validcheck({ list: [1] }); // Fail (min 2 elements)check({ list: [1, -7] }); // Fail (negative number)

Example with an object list:

const schema = { users: { type: "array", items: { type: "object", props: { id: { type: "number", positive: true }, name: { type: "string", empty: false }, status: "boolean" } } }}const check = v.compile(schema)check({ users: [ { id: 1, name: "John", status: true }, { id: 2, name: "Jane", status: true }, { id: 3, name: "Bill", status: false } ]}); // Valid

Example for enum:

const schema = { roles: { type: "array", items: "string", enum: [ "user", "admin" ] }}const check = v.compile(schema)check({ roles: ["user"] }); // Validcheck({ roles: ["user", "admin"] }); // Validcheck({ roles: ["guest"] }); // Fail

Example for unique:

const schema = { roles: { type: "array", unique: true }}const check = v.compile(schema);check({ roles: ["user"] }); // Validcheck({ roles: [{role:"user"},{role:"admin"},{role:"user"}] }); // Validcheck({ roles: ["user", "admin", "user"] }); // Failcheck({ roles: [1, 2, 1] }); // Fail

Example for convert:

const schema = { roles: { type: "array", items: 'string', convert: true }}const check = v.compile(schema);check({ roles: ["user"] }); // Validcheck({ roles: "user" }); // Valid// After both validation: roles = ["user"]

Properties

Property	Default	Description
`empty`	`true`	If `true`, the validator accepts an empty array `[]`.
`min`	`null`	Minimum count of elements.
`max`	`null`	Maximum count of elements.
`length`	`null`	Fix count of elements.
`contains`	`null`	The array must contain this element too.
`unique`	`null`	The array must be unique (array of objects is always unique).
`enum`	`null`	Every element must be an element of the `enum` array.
`items`	`null`	Schema for array items.
`convert`	`null`	Wrap value into array if different type provided

`boolean`

This is a Boolean validator.

const schema = { status: { type: "boolean" }}const check = v.compile(schema);check({ status: true }); // Validcheck({ status: false }); // Validcheck({ status: 1 }); // Failcheck({ status: "true" }); // Fail

Properties

Property	Default	Description
`convert`	`false`	if `true` and the type is not `Boolean`, it will be converted. `1`, `"true"`, `"1"`, `"on"` will be true. `0`, `"false"`, `"0"`, `"off"` will be false. It's a sanitizer, it will change the value in the original object.

Example for convert:

const schema = { status: { type: "boolean", convert: true}};const check = v.compile(schema);check({ status: "true" }); // Valid

`class`

This is a Class validator to check the value is an instance of a Class.

const schema = { rawData: { type: "class", instanceOf: Buffer }}const check = v.compile(schema);check({ rawData: Buffer.from([1, 2, 3]) }); // Validcheck({ rawData: 100 }); // Fail

Properties

Property	Default	Description
`instanceOf`	`null`	Checked Class.

`currency`

This is a Currency validator to check if the value is a valid currency string.

const schema = { money_amount: { type: "currency", currencySymbol: '$' }}const check = v.compile(schema);check({ money_amount: '$12.99'}); // Validcheck({ money_amount: '$0.99'}); // Validcheck({ money_amount: '$12,345.99'}); // Validcheck({ money_amount: '$123,456.99'}); // Validcheck({ money_amount: '$1234,567.99'}); // Failcheck({ money_amount: '$1,23,456.99'}); // Failcheck({ money_amount: '$12,34.5.99' }); // Fail

Properties

Property	Default	Description
`currencySymbol`	`null`	The currency symbol expected in string (as prefix).
`symbolOptional`	`false`	Toggle to make the symbol optional in string, although, if present it would only allow the currencySymbol.
`thousandSeparator`	`,`	Thousand place separator character.
`decimalSeparator`	`.`	Decimal place character.
`customRegex`	`null`	Custom regular expression, to validate currency strings (For eg: /[0-9]*/g).

`date`

This is a Date validator.

const schema = { dob: { type: "date" }}const check = v.compile(schema);check({ dob: new Date() }); // Validcheck({ dob: new Date(1488876927958) }); // Validcheck({ dob: 1488876927958 }); // Fail

Properties

Property	Default	Description
`convert`	`false`	if `true` and the type is not `Date`, try to convert with `new Date()`. It's a sanitizer, it will change the value in the original object.

Example for convert:

const schema = { dob: { type: "date", convert: true}};const check = v.compile(schema);check({ dob: 1488876927958 }, ); // Valid

`email`

This is an e-mail address validator.

Properties

Property	Default	Description
`empty`	`false`	If `true`, the validator accepts an empty array `""`.
`mode`	`quick`	Checker method. Can be `quick` or `precise`.
`normalize`	`false`	Normalize the e-mail address (trim & lower-case). It's a sanitizer, it will change the value in the original object.
`min`	`null`	Minimum value length.
`max`	`null`	Maximum value length.

`enum`

This is an enum validator.

const schema = { sex: { type: "enum", values: ["male", "female"] }}const check = v.compile(schema);check({ sex: "male" }); // Validcheck({ sex: "female" }); // Validcheck({ sex: "other" }); // Fail

Properties

Property	Default	Description
`values`	`null`	The valid values.

`equal`

This is an equal value validator. It checks a value with a static value or with another property.

Example with static value:

const schema = { agreeTerms: { type: "equal", value: true, strict: true } // strict means `===`}const check = v.compile(schema);check({ agreeTerms: true }); // Validcheck({ agreeTerms: false }); // Fail

Example with other field:

const schema = { password: { type: "string", min: 6 }, confirmPassword: { type: "equal", field: "password" }}const check = v.compile(schema);check({ password: "123456", confirmPassword: "123456" }); // Validcheck({ password: "123456", confirmPassword: "pass1234" }); // Fail

Properties

Property	Default	Description
`value`	`undefined`	The expected value. It can be any primitive types.
`strict`	`false`	if `true`, it uses strict equal `===` for checking.

`forbidden`

This validator returns an error if the property exists in the object.

const schema = { password: { type: "forbidden" }}const check = v.compile(schema);check({ user: "John" }); // Validcheck({ user: "John", password: "pass1234" }); // Fail

Properties

Property	Default	Description
`remove`	`false`	If `true`, the value will be removed in the original object. It's a sanitizer, it will change the value in the original object.

Example for remove:

const schema = { user: { type: "string" }, token: { type: "forbidden", remove: true }};const check = v.compile(schema);const obj = { user: "John", token: "123456"}check(obj); // Validconsole.log(obj);/*{ user: "John", token: undefined}*/

`function`

This a Function type validator.

const schema = { show: { type: "function" }}const check = v.compile(schema);check({ show: function() {} }); // Validcheck({ show: Date.now }); // Validcheck({ show: "function" }); // Fail

`luhn`

This is an Luhn validator.Luhn algorithm checksumCredit Card numbers, IMEI numbers, National Provider Identifier numbers and others

const schema = { cc: { type: "luhn" }}const check = v.compile(schema);check({ cc: "452373989901198" }); // Validcheck({ cc: 452373989901198 }); // Validcheck({ cc: "4523-739-8990-1198" }); // Validcheck({ cc: "452373989901199" }); // Fail

`mac`

This is an MAC addresses validator.

const schema = { mac: { type: "mac" }}const check = v.compile(schema);check({ mac: "01:C8:95:4B:65:FE" }); // Validcheck({ mac: "01:c8:95:4b:65:fe"); // Validcheck({ mac: "01C8.954B.65FE" }); // Validcheck({ mac: "01c8.954b.65fe"); // Validcheck({ mac: "01-C8-95-4B-65-FE" }); // Validcheck({ mac: "01-c8-95-4b-65-fe" }); // Validcheck({ mac: "01C8954B65FE" }); // Fail

`multi`

This is a multiple definitions validator.

const schema = { status: { type: "multi", rules: [ { type: "boolean" }, { type: "number" } ], default: true }}const check = v.compile(schema);check({ status: true }); // Validcheck({ status: false }); // Validcheck({ status: 1 }); // Validcheck({ status: 0 }); // Validcheck({ status: "yes" }); // Fail

Shorthand multiple definitions:

const schema = { status: [ "boolean", "number" ]}const check = v.compile(schema);check({ status: true }); // Validcheck({ status: false }); // Validcheck({ status: 1 }); // Validcheck({ status: 0 }); // Validcheck({ status: "yes" }); // Fail

`number`

This is a Number validator.

const schema = { age: { type: "number" }}const check = v.compile(schema);check({ age: 123 }); // Validcheck({ age: 5.65 }); // Validcheck({ age: "100" }); // Fail

Properties

Property	Default	Description
`min`	`null`	Minimum value.
`max`	`null`	Maximum value.
`equal`	`null`	Fixed value.
`notEqual`	`null`	Can't be equal to this value.
`integer`	`false`	The value must be a non-decimal value.
`positive`	`false`	The value must be greater than zero.
`negative`	`false`	The value must be less than zero.
`convert`	`false`	if `true` and the type is not `Number`, it's converted with `Number()`. It's a sanitizer, it will change the value in the original object.

`object`

This is a nested object validator.

const schema = { address: { type: "object", strict: true, props: { country: { type: "string" }, city: "string", // short-hand zip: "number" // short-hand } }}const check = v.compile(schema);check({ address: { country: "Italy", city: "Rome", zip: 12345 }}); // Validcheck({ address: { country: "Italy", city: "Rome" }}); // Fail ("The 'address.zip' field is required!")check({ address: { country: "Italy", city: "Rome", zip: 12345, state: "IT" }}); // Fail ("The 'address.state' is an additional field!")

Properties

Property	Default	Description
`strict`	`false`	If `true` any properties which are not defined on the schema will throw an error. If `remove` all additional properties will be removed from the original object. It's a sanitizer, it will change the original object.
`minProps`	`null`	If set to a number N, will throw an error if the object has fewer than N properties.
`maxProps`	`null`	If set to a number N, will throw an error if the object has more than N properties.

schema = { address: { type: "object", strict: "remove", props: { country: { type: "string" }, city: "string", // short-hand zip: "number" // short-hand } }}let obj = { address: { country: "Italy", city: "Rome", zip: 12345, state: "IT" }};const check = v.compile(schema);check(obj); // Validconsole.log(obj);/*{ address: { country: "Italy", city: "Rome", zip: 12345 } }*/

schema = { address: { type: "object", minProps: 2, props: { country: { type: "string" }, city: { type: "string", optional: true }, zip: { type: "number", optional: true } } }}const check = v.compile(schema);obj = { address: { country: "Italy", city: "Rome", zip: 12345, state: "IT" }}check(obj); // Validobj = { address: { country: "Italy", }}check(obj); // Fail// [// {// type: 'objectMinProps',// message: "The object 'address' must contain at least 2 properties.",// field: 'address',// expected: 2,// actual: 1// }// ]

`record`

This validator allows to check an object with arbitrary keys.

const schema = { surnameGroups: { type: 'record', key: { type: 'string', alpha: true }, value: { type: 'array', items: 'string' } }};const check = v.compile(schema);check({ surnameGroups: { Doe: ['Jane', 'John'], Williams: ['Bill'] } }); // Validcheck({ surnameGroups: { Doe1: ['Jane', 'John'] } }); // Failcheck({ surnameGroups: { Doe: [1, 'Jane'] } }); // Fail

Properties

Property	Default	Description
`key`	`string`	Key validation rule (It is reasonable to use only the `string` rule).
`value`	`any`	Value validation rule.

`string`

This is a String validator.

const schema = { name: { type: "string" }}const check = v.compile(schema);check({ name: "John" }); // Validcheck({ name: "" }); // Validcheck({ name: 123 }); // Fail

Properties

Property	Default	Description
`empty`	`true`	If `true`, the validator accepts an empty string `""`.
`min`	`null`	Minimum value length.
`max`	`null`	Maximum value length.
`length`	`null`	Fixed value length.
`pattern`	`null`	Regex pattern.
`contains`	`null`	The value must contain this text.
`enum`	`null`	The value must be an element of the `enum` array.
`alpha`	`null`	The value must be an alphabetic string.
`numeric`	`null`	The value must be a numeric string.
`alphanum`	`null`	The value must be an alphanumeric string.
`alphadash`	`null`	The value must be an alphabetic string that contains dashes.
`hex`	`null`	The value must be a hex string.
`singleLine`	`null`	The value must be a single line string.
`base64`	`null`	The value must be a base64 string.
`trim`	`null`	If `true`, the value will be trimmed. It's a sanitizer, it will change the value in the original object.
`trimLeft`	`null`	If `true`, the value will be left trimmed. It's a sanitizer, it will change the value in the original object.
`trimRight`	`null`	If `true`, the value will be right trimmed. It's a sanitizer, it will change the value in the original object.
`padStart`	`null`	If it's a number, the value will be left padded. It's a sanitizer, it will change the value in the original object.
`padEnd`	`null`	If it's a number, the value will be right padded. It's a sanitizer, it will change the value in the original object.
`padChar`	`" "`	The padding character for the `padStart` and `padEnd`.
`lowercase`	`null`	If `true`, the value will be lower-cased. It's a sanitizer, it will change the value in the original object.
`uppercase`	`null`	If `true`, the value will be upper-cased. It's a sanitizer, it will change the value in the original object.
`localeLowercase`	`null`	If `true`, the value will be locale lower-cased. It's a sanitizer, it will change the value in the original object.
`localeUppercase`	`null`	If `true`, the value will be locale upper-cased. It's a sanitizer, it will change the value in the original object.
`convert`	`false`	if `true` and the type is not a `String`, it's converted with `String()`. It's a sanitizer, it will change the value in the original object.

Sanitization example

const schema = { username: { type: "string", min: 3, trim: true, lowercase: true}}const check = v.compile(schema);const obj = { username: " Icebob "};check(obj); // Validconsole.log(obj);/*{ username: "icebob"}*/

`tuple`

This validator checks if a value is an Array with the elements order as described by the schema.

Simple example:

const schema = { list: "tuple" };const check = v.compile(schema);check({ list: [] }); // Validcheck({ list: [1, 2] }); // Validcheck({ list: ["RON", 100, true] }); // Validcheck({ list: 94 }); // Fail (not an array)

Example with items:

const schema = { grade: { type: "tuple", items: ["string", "number"] }}const check = v.compile(schema);check({ grade: ["David", 85] }); // Validcheck({ grade: [85, "David"] }); // Fail (wrong position)check({ grade: ["Cami"] }); // Fail (require 2 elements)

Example with a more detailed schema:

const schema = { location: { type: "tuple", items: [ "string", { type: "tuple", empty: false, items: [ { type: "number", min: 35, max: 45 }, { type: "number", min: -75, max: -65 } ] } ] }}const check = v.compile(schema);check({ location: ['New York', [40.7127281, -74.0060152]] }); // Validcheck({ location: ['New York', [50.0000000, -74.0060152]] }); // Failcheck({ location: ['New York', []] }); // Fail (empty array)

Properties

Property	Default	Description
`empty`	`true`	If `true`, the validator accepts an empty array `[]`.
`items`	`undefined`	Exact schema of the value items

`url`

This is an URL validator.

const schema = { url: { type: "url" }}const check = v.compile(schema);check({ url: "http://google.com" }); // Validcheck({ url: "https://github.com/icebob" }); // Validcheck({ url: "www.facebook.com" }); // Fail

Properties

Property	Default	Description
`empty`	`false`	If `true`, the validator accepts an empty string `""`.

`uuid`

This is an UUID validator.

const schema = { uuid: { type: "uuid" }}const check = v.compile(schema);check({ uuid: "00000000-0000-0000-0000-000000000000" }); // Valid Nil UUIDcheck({ uuid: "10ba038e-48da-487b-96e8-8d3b99b6d18a" }); // Valid UUIDv4check({ uuid: "9a7b330a-a736-51e5-af7f-feaf819cdc9f" }); // Valid UUIDv5check({ uuid: "10ba038e-48da-487b-96e8-8d3b99b6d18a", version: 5 }); // Fail

Properties

Property	Default	Description
`version`	`null`	UUID version in range 0-6. The `null` disables version checking.

`objectID`

You can validate BSON/MongoDB ObjectID's

const { ObjectID } = require("mongodb") // or anywhere else const schema = { id: { type: "objectID", ObjectID // passing the ObjectID class } }const check = v.compile(schema);check({ id: "5f082780b00cc7401fb8e8fc" }) // okcheck({ id: new ObjectID() }) // okcheck({ id: "5f082780b00cc7401fb8e8" }) // Error

Pro tip: By using defaults props for objectID rule, No longer needed to pass ObjectID class in validation schema:

const { ObjectID } = require("mongodb") // or anywhere else const v = new Validator({ defaults: { objectID: { ObjectID } }})const schema = { id: "objectID" }

Properties

Property	Default	Description
`convert`	`false`	If `true`, the validator converts ObjectID HexString representation to ObjectID `instance`, if `hexString` the validator converts to HexString

You can also create your custom validator.

const v = new Validator({ messages: { // Register our new error message text evenNumber: "The '{field}' field must be an even number! Actual: {actual}" }});// Register a custom 'even' validatorv.add("even", function({ schema, messages }, path, context) { return { source: ` if (value % 2 != 0) ${this.makeError({ type: "evenNumber", actual: "value", messages })} return value; ` };});const schema = { name: { type: "string", min: 3, max: 255 }, age: { type: "even" }};const check = v.compile(schema);console.log(check({ name: "John", age: 20 }, schema));// Returns: trueconsole.log(check({ name: "John", age: 19 }, schema));/* Returns an array with errors: [{ type: 'evenNumber', expected: null, actual: 19, field: 'age', message: 'The \'age\' field must be an even number! Actual: 19' }]*/

Or you can use the custom type with an inline checker function:

const v = new Validator({ useNewCustomCheckerFunction: true, // using new version messages: { // Register our new error message text weightMin: "The weight must be greater than {expected}! Actual: {actual}" }});const schema = { name: { type: "string", min: 3, max: 255 }, weight: { type: "custom", minWeight: 10, check(value, errors, schema) { if (value < minWeight) errors.push({ type: "weightMin", expected: schema.minWeight, actual: value }); if (value > 100) value = 100 return value } }};const check = v.compile(schema);console.log(check({ name: "John", weight: 50 }, schema));// Returns: trueconsole.log(check({ name: "John", weight: 8 }, schema));/* Returns an array with errors: [{ type: 'weightMin', expected: 10, actual: 8, field: 'weight', message: 'The weight must be greater than 10! Actual: 8' }]*/const o = { name: "John", weight: 110 }console.log(check(o, schema));/* Returns: true o.weight is 100*/

Please note: the custom function must return the value. It means you can also sanitize it.

Custom validation for built-in rules

You can define a custom function in the schema for built-in rules. With it you can extend any built-in rules.

const v = new Validator({ useNewCustomCheckerFunction: true, // using new version messages: { // Register our new error message text phoneNumber: "The phone number must be started with '+'!" }});const schema = { name: { type: "string", min: 3, max: 255 }, phone: { type: "string", length: 15, custom: (v, errors) => { if (!v.startsWith("+")) errors.push({ type: "phoneNumber" }) return v.replace(/[^\d+]/g, ""); // Sanitize: remove all special chars except numbers } }};const check = v.compile(schema);console.log(check({ name: "John", phone: "+36-70-123-4567" }));// Returns: trueconsole.log(check({ name: "John", phone: "36-70-123-4567" }));/* Returns an array with errors: [{ message: "The phone number must be started with '+'!", field: 'phone', type: 'phoneNumber' }]*/

Please note: the custom function must return the value. It means you can also sanitize it.

Chaining custom functions and global definitions

You can define the custom property as an array of functions, allowing you to chain various validation logics.

Additionally, you can define custom functions globally, making them reusable.

let v = new Validator({debug: true,useNewCustomCheckerFunction: true,messages: {// Register our new error message textevenNumber: "The '{field}' field must be an even number! Actual: {actual}",realNumber: "The '{field}' field must be a real number! Actual: {actual}",notPermitNumber: "The '{field}' cannot have the value {actual}", compareGt: "The '{field}' field must be greater than {gt}! Actual: {actual}", compareGte: "The '{field}' field must be greater than or equal to {gte}! Actual: {actual}", compareLt: "The '{field}' field must be less than {lt}! Actual: {actual}", compareLte: "The '{field}' field must be less than or equal to {lte}! Actual: {actual}"},customFunctions:{even: (value, errors)=>{if(value % 2 != 0 ){errors.push({ type: "evenNumber", actual: value });}return value;},real: (value, errors)=>{if(value <0 ){errors.push({ type: "realNumber", actual: value });}return value;}, compare: (value, errors, schema)=>{if( typeof schema.custom.gt==="number" && value <= schema.custom.gt ){errors.push({ type: "compareGt", actual: value, gt: schema.custom.gt });}if( typeof schema.custom.gte==="number" && value < schema.custom.gte ){errors.push({ type: "compareGte", actual: value, gte: schema.custom.gte });}if( typeof schema.custom.lt==="number" && value >= schema.custom.lt ){errors.push({ type: "compareLt", actual: value, lt: schema.custom.lt });}if( typeof schema.custom.lte==="number" && value > schema.custom.lte ){errors.push({ type: "compareLte", actual: value, lte: schema.custom.lte });}return value;}}});const schema = {people:{type: "number",custom: [ "compare|gte:-100|lt:200", // extended definition with additional parameters - equal to: {type:"compare",gte:-100, lt:200}, "even","real",function (value, errors){if(value === "3" ){errors.push({ type: "notPermitNumber", actual: value });}return value;}]}};console.log(v.validate({people:-200}, schema));console.log(v.validate({people:200}, schema));console.log(v.validate({people:5}, schema));console.log(v.validate({people:-5}, schema));console.log(v.validate({people:3}, schema));

Asynchronous custom validations

You can also use async custom validators. This can be useful if you need to check something in a database or in a remote location.In this case you should use async/await keywords, or return a Promise in the custom validator functions.

This implementation uses async/await keywords. So this feature works only on environments which supports async/await:
Chrome > 55
Firefox > 52
Edge > 15
NodeJS > 8.x (or 7.6 with harmony)
Deno (all versions)

To enable async mode, you should set $$async: true in the root of your schema.

Example with custom checker function

const v = new Validator({ useNewCustomCheckerFunction: true, // using new version messages: { // Register our new error message text unique: "The username is already exist" }});const schema = { $$async: true, name: { type: "string" }, username: { type: "string", min: 2, custom: async (v, errors) => { // E.g. checking in the DB that the value is unique. const res = await DB.checkUsername(v); if (!res) errors.push({ type: "unique", actual: value }); return v; } } // ...};const check = v.compile(schema);const res = await check(user);console.log("Result:", res);

The compiled check function contains an async property, so you can check if it returns a Promise or not.

const check = v.compile(schema);console.log("Is async?", check.async);

Meta information for custom validators

You can pass any extra meta information for the custom validators which is available via context.meta.

const schema = { name: { type: "string", custom: (value, errors, schema, name, parent, context) => { // Access to the meta return context.meta.a; } },};const check = v.compile(schema);const res = check(obj, { // Passes meta information meta: { a: "from-meta" }});

You can set your custom messages in the validator constructor.

const Validator = require("fastest-validator");const v = new Validator({ messages: { stringMin: "A(z) '{field}' mező túl rövid. Minimum: {expected}, Jelenleg: {actual}", stringMax: "A(z) '{field}' mező túl hosszú. Minimum: {expected}, Jelenleg: {actual}" }});const schema = { name: { type: "string", min: 6 }}const check = v.compile(schema);check({ name: "John" });/* Returns:[ { type: 'stringMin', expected: 6, actual: 4, field: 'name', message: 'A(z) \'name\' mező túl rövid. Minimum: 6, Jelenleg: 4' }]*/

Sometimes the standard messages are too generic. You can customize messages per validation type per field:

const Validator = require("fastest-validator");const v = new Validator();const schema = { firstname: { type: "string", min: 6, messages: { string: "Please check your firstname", stringMin: "Your firstname is too short" } }, lastname: { type: "string", min: 6, messages: { string: "Please check your lastname", stringMin: "Your lastname is too short" } }}const check = v.compile(schema);check({ firstname: "John", lastname: 23 });/* Returns:[ { type: 'stringMin', expected: 6, actual: 4, field: 'firstname', message: 'Your firstname is too short' }, { type: 'string', expected: undefined, actual: undefined, field: 'lastname', message: 'Please check your lastname' }]*/

You can apply plugins:

// Plugin Sidefunction myPlugin(validator){ // you can modify validator here // e.g.: validator.add(...)}// Validator Sideconst v = new Validator();v.plugin(myPlugin)

Name	Default text
`required`	The '{field}' field is required.
`string`	The '{field}' field must be a string.
`stringEmpty`	The '{field}' field must not be empty.
`stringMin`	The '{field}' field length must be greater than or equal to {expected} characters long.
`stringMax`	The '{field}' field length must be less than or equal to {expected} characters long.
`stringLength`	The '{field}' field length must be {expected} characters long.
`stringPattern`	The '{field}' field fails to match the required pattern.
`stringContains`	The '{field}' field must contain the '{expected}' text.
`stringEnum`	The '{field}' field does not match any of the allowed values.
`stringNumeric`	The '{field}' field must be a numeric string.
`stringAlpha`	The '{field}' field must be an alphabetic string.
`stringAlphanum`	The '{field}' field must be an alphanumeric string.
`stringAlphadash`	The '{field}' field must be an alphadash string.
`stringHex`	The '{field}' field must be a hex string.
`stringSingleLine`	The '{field}' field must be a single line string.
`stringBase64`	The '{field}' field must be a base64 string.
`number`	The '{field}' field must be a number.
`numberMin`	The '{field}' field must be greater than or equal to {expected}.
`numberMax`	The '{field}' field must be less than or equal to {expected}.
`numberEqual`	The '{field}' field must be equal to {expected}.
`numberNotEqual`	The '{field}' field can't be equal to {expected}.
`numberInteger`	The '{field}' field must be an integer.
`numberPositive`	The '{field}' field must be a positive number.
`numberNegative`	The '{field}' field must be a negative number.
`array`	The '{field}' field must be an array.
`arrayEmpty`	The '{field}' field must not be an empty array.
`arrayMin`	The '{field}' field must contain at least {expected} items.
`arrayMax`	The '{field}' field must contain less than or equal to {expected} items.
`arrayLength`	The '{field}' field must contain {expected} items.
`arrayContains`	The '{field}' field must contain the '{expected}' item.
`arrayUnique`	The '{actual}' value in '{field}' field does not unique the '{expected}' values.
`arrayEnum`	The '{actual}' value in '{field}' field does not match any of the '{expected}' values.
`tuple`	The '{field}' field must be an array.
`tupleEmpty`	The '{field}' field must not be an empty array.
`tupleLength`	The '{field}' field must contain {expected} items.
`boolean`	The '{field}' field must be a boolean.
`function`	The '{field}' field must be a function.
`date`	The '{field}' field must be a Date.
`dateMin`	The '{field}' field must be greater than or equal to {expected}.
`dateMax`	The '{field}' field must be less than or equal to {expected}.
`forbidden`	The '{field}' field is forbidden.
`email`	The '{field}' field must be a valid e-mail.
`emailEmpty`	The '{field}' field must not be empty.
`emailMin`	The '{field}' field length must be greater than or equal to {expected} characters long.
`emailMax`	The '{field}' field length must be less than or equal to {expected} characters long.
`url`	The '{field}' field must be a valid URL.
`enumValue`	The '{field}' field value '{expected}' does not match any of the allowed values.
`equalValue`	The '{field}' field value must be equal to '{expected}'.
`equalField`	The '{field}' field value must be equal to '{expected}' field value.
`object`	The '{field}' must be an Object.
`objectStrict`	The object '{field}' contains forbidden keys: '{actual}'.
`objectMinProps`	"The object '{field}' must contain at least {expected} properties.
`objectMaxProps`	"The object '{field}' must contain {expected} properties at most.
`uuid`	The '{field}' field must be a valid UUID.
`uuidVersion`	The '{field}' field must be a valid UUID version provided.
`mac`	The '{field}' field must be a valid MAC address.
`luhn`	The '{field}' field must be a valid checksum luhn.

Message fields

Name	Description
`field`	The field name
`expected`	The expected value
`actual`	The actual value

In some case, you will need to do something with the validation schema .Like reusing the validator to pass custom settings, you can use properties starting with $$

const check = v.compile({ $$name: 'Person', $$description: 'write a description about this schema', firstName: { type: "string" }, lastName: { type: "string" }, birthDate: { type: "date" } });

npm run dev

npm test

Coverage report

-----------------|----------|----------|----------|----------|-------------------|File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |-----------------|----------|----------|----------|----------|-------------------|All files | 100 | 97.73 | 100 | 100 | | lib | 100 | 100 | 100 | 100 | | messages.js | 100 | 100 | 100 | 100 | | validator.js | 100 | 100 | 100 | 100 | | lib/helpers | 100 | 100 | 100 | 100 | | deep-extend.js | 100 | 100 | 100 | 100 | | flatten.js | 100 | 100 | 100 | 100 | | lib/rules | 100 | 96.43 | 100 | 100 | | any.js | 100 | 100 | 100 | 100 | | array.js | 100 | 100 | 100 | 100 | | boolean.js | 100 | 100 | 100 | 100 | | custom.js | 100 | 50 | 100 | 100 | 6 | date.js | 100 | 100 | 100 | 100 | | email.js | 100 | 100 | 100 | 100 | | enum.js | 100 | 50 | 100 | 100 | 6 | equal.js | 100 | 100 | 100 | 100 | | forbidden.js | 100 | 100 | 100 | 100 | | function.js | 100 | 100 | 100 | 100 | | luhn.js | 100 | 100 | 100 | 100 | | mac.js | 100 | 100 | 100 | 100 | | multi.js | 100 | 100 | 100 | 100 | | number.js | 100 | 100 | 100 | 100 | | object.js | 100 | 100 | 100 | 100 | | string.js | 100 | 95.83 | 100 | 100 | 55,63 | tuple.js | 100 | 100 | 100 | 100 | | url.js | 100 | 100 | 100 | 100 | | uuid.js | 100 | 100 | 100 | 100 | |-----------------|----------|----------|----------|----------|-------------------|

Please send pull requests improving the usage and fixing bugs, improving documentation and providing better examples, or providing some tests, because these things are important.

fastest-validator is available under the MIT license.

fastest-validator (2024)

Key features

How fast?

Approach

NPM

Validate

Halting

Browser usage

Deno usage

Supported frameworks

Optional

Nullable

Nullable and default values

Considering null as a value

Remove additional fields

Default values

Array of X

Nested objects

any

array

Properties

boolean

Properties

class

Properties

currency

Properties

date

Properties

email

Properties

enum

Properties

equal

Properties

forbidden

Properties

function

luhn

mac

multi

number

Properties

object

Properties

record

Properties

string

Properties

tuple

Properties

url

Properties

uuid

Properties

objectID

Properties

Custom validation for built-in rules

Chaining custom functions and global definitions

Asynchronous custom validations

Meta information for custom validators

Message fields

Coverage report

Considering `null` as a value

`any`

`array`

`boolean`

`class`

`currency`

`date`

`email`

`enum`

`equal`

`forbidden`

`function`

`luhn`

`mac`

`multi`

`number`

`object`

`record`

`string`

`tuple`

`url`

`uuid`

`objectID`