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 v_alidatio_n. 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_ ...

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Create validations very easily with its chainable API:

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

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

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

So fluent that it looks like English:

`javascript
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.

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

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

v8n.extend({ foo });
`

v8n will treat them like built-in ones:

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

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

_specialNumber.js_

`javascript
import v8n from "v8n";

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

and use them anywhere you want:

`javascript
import specialNumber from "../specialNumber";

specialNumber.test(63); // true
`

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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!

`javascript
// 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
`

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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:

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

#### Exception based validation:

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

#### Getting all failures:

`javascript
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:

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

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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.

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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.

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All these incredible features for just a few bytes:

!npm bundle size (minified + gzip)

Architecture

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

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

`javascript
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.

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

`javascript
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