Quartet 9: Allegro | Brevity and simplicity

When I created the library for data validation quartet, I took the following landmarks:

• TypeScript
• Brevity and simplicity
• Performance

In this article I will show how the library quartetunderstands what the words “Short” and “Simple” mean in the context of the approach to validation.

How does it work quartet?

When is it needed? It is needed when data validation is needed.
What is validation? Check data for compliance. Most often types.
How does quartetthis help? It creates a validation function based on a declarative description of requirements - a scheme. The compiler function vconverts the circuit into a validation function. Also v, prepared schemes and methods are stored inside to create more complex schemes. See the documentation for more details .

How it works?

1. You write a scheme
2. You give it to the input of the compiler function vto get the validation function.
3. The validation function is ready to use!

Let's quartet validate all the data without straining the brain in seven approaches.

.

:

type Answer = 42;

quartet:

const answerSchema = 42;

- :

import { v } from "quartet";
const checkAnswer = v(42);

. — .

, . — .

. , , .

const checkNumber = (x) => typeof x === "number";
const checkString = (x) => typeof x === "string";
const checkBoolean = (x) => typeof x === "boolean";
const checkSymbol = (x) => typeof x === "symbol";
// ...

:

const checkSomeType = x => typeof x === "<type>",  <type> –   

, :

, :

const checkNumber = v(v.number);
//  , 
const checkNumber = (x) => typeof x === "number";

quartet

:

const checkFunction = v(v.function);
//  , 
const checkFunction = (x) => typeof x === "function";

. C — v..

«»

:

type NullableString = string | null;

quartet:

const nullableStringSchema = [v.string, null];

:

const checkNullableString = v([v.string, null]);

:

type VariantSchema = Schema[];

. – .

«»

type Password =  string //     8-      1   .

. v.minLength() v.test(RegExp)

const stringSchema = v.string;
const min8Schema = v.minLength(8);
const atLeastOneDigitSchema = v.test(/\d/);
const atLeastOneLetterSchema = v.test(/[A-Za-z]/);

v.and():

const passwordSchema = v.and(
    stringSchema,
    min8Schema,
    atLeastOneDigitSchema,
    atLeastOneLetterSchema,
)

. v.and(, , ...).

Person:

interface Person {
    name: string
    age: number
}

, Person?
, name age. string number. !

, , .

— !

:

const personSchema = {
  name: v.string,
  age: v.number,
};

:

interface ObjectInterfaceSchema {
  [propertyName: string]: Schema;
}

. — , — , — .

:

type Numbers = number[];

v.arrayOf(). .

const checkNumbers = v(v.arrayOf(v.number));

. v.arrayOf( ).

quartet.

. є v.custom( ):

const evenSchema = v.custom((x) => x % 2 === 0)
const evenNumberSchema = v.and(
  v.number,
  evenSchema,
);

. v.custom( ).

• — .
• C — v..
• — .
• v.and(, , ...).
• — , — , — .
• v.arrayOf( ).
• v.custom( ).

P.S.

. quartet :
. 4 , .

, !