v8n

The ultimate JavaScript validation library you've ever needed.
Dead simple fluent API. Customizable. Reusable.

Installation - Documentation - API

Introducing v8n

v8n is an acronym for validation. Notice that it has exactly
eight letters between v and n in the “validation” word. This is the
same pattern we are used to seeing with i18n, a11y, l10n …

Chainable API

Create validations very easily with its chainable API:

v8n()
  .string()
  .minLength(5)
  .first("H")
  .last("o")
  .test("Hello"); // true

Incredibly fluent

Mix rules and modifiers together to create complex validations with
great ease and fluency:

v8n()
  .array()
  .every.number()
  .not.some.negative()
  .test([1, 2, -3]); // false - no negative please!

So fluent that it looks like English:

v8n()
  .some.not.uppercase() // expects that some character is not uppercase
  .test("Hello"); // true

v8n()
  .not.some.uppercase() // expects that no character is uppercase
  .test("Hello"); // false

Notice how we made very different validation strategies just by changing the
order of the modifiers. It’s so intuitive that seems to be impossible, but this
is v8n.

Customizable

Create your own custom validation rules in a very intuitive way:

function foo() {
  return value => value === "bar";
}

v8n.extend({ foo });

v8n will treat them like built-in ones:

v8n()
  .string()
  .foo()
  .test("bar"); // true

Reusable

Export validations just like you’re used to do with your JavaScript modules:

specialNumber.js

import v8n from "v8n";

export default v8n()
  .number()
  .between(50, 100)
  .not.even();

and use them anywhere you want:

import specialNumber from "../specialNumber";

specialNumber.test(63); // true

For any kind of data

Use v8n to validate your data regardless of its type. You can validate
primitives, arrays, objects and whatever you want! You can also use them
together!

// numbers
v8n()
  .number()
  .between(5, 10)
  .test(7); //true

// strings
v8n()
  .string()
  .minLength(3)
  .test("foo"); // true

// arrays
v8n()
  .array()
  .every.even()
  .test([2, 4, 6]); // true

// objects
const myData = { id: "fe03" };

v8n()
  .schema({
    id: v8n().string()
  })
  .test(myData); // true

For any kind of validation

Do simple validations with boolean based tests. Get more information about your
validation process with exception based tests. And of course, perform
asynchronous tests as well. All in one library.

Boolean based validation:

v8n()
  .string()
  .first("H")
  .test("Hello"); // true

Exception based validation:

try {
  v8n()
    .string()
    .first("b")
    .check("foo");
} catch (ex) {
  console.log(ex.rule.name); // first
}

Getting all failures:

const failed = v8n()
  .string()
  .minLength(3)
  .testAll(10);

failed;
// [
//   ValidationError { rule: { name: "string", ... } },
//   ValidationError { rule: { name: "minLength", ... } }
// ]

Async validation:

If your validation strategy has some rule that performs time consuming
validation, like a back-end check, you should use asynchronous validation:

v8n()
  .somAsyncRule()
  .testAsync("foo") // returns a Promise
  .then(result => {
    /* valid! */
  })
  .catch(ex => {
    /* invalid! */
  });

Shareable

Share your rules with the world, and use theirs as well.

Create useful validation rules and share them with the open source community,
and let people around the world validate without reinventing the wheel.

Ready to use!

There are a lot of built-in rules and modifiers for you to use already
implemented in v8n’s core. Take a look at all of them in our
API page. But if you can’t find what you
need, go ahead and make it.

Tiny!

All these incredible features for just a few bytes:

Architecture

The v8n core is composed of rules and modifiers. They are used together
to build complex validations in an easy way.

Rules

Rules are the heart of the v8n ecosystem. You use them to build your
validation strategies:

v8n()
  .string()
  .minLength(3)
  .test("Hello"); // true

In this code snippet, we’re using two rules (string and minLength) to build
our validation strategy. So our validated value ("Hello") is valid because
it’s a string and it is at least 3 characters long.

Rules can be more powerful if used along with modifiers. Learn about them in
the next section.

Modifiers

Modifiers can be used to change rules meaning. For example, you can use the
not modifier to expect the reversed result from a rule:

v8n()
  .not.equal(5)
  .test(5); // false

You can check all available modifiers on our documentation page.

Modifiers are very powerful. They work as decorators for rules. When used
together, they allow you to build very complex validations.

Contribute

Contributions of any kind are welcome! Read our
CONTRIBUTING guide.

License

MIT License