@illavv/run_typer NPM

Typer - Type Checking & Validation Library

Typer is a powerful TypeScript utility library for type checking and validation. It provides a structured and flexible way to verify data types, enforce constraints, and enhance runtime safety in JavaScript and TypeScript applications.

🚀 Features

Comprehensive Type Checking: Supports checking for primitive types, complex types, and user-defined custom types.
Extensible Type System: Register and unregister your own validation functions.
Schema-Based Validation: Easily validate object structures.
Strict Mode Compatibility: Works seamlessly with TypeScript's strict mode.
Asynchronous & Synchronous Support: Ensures correct function return types, even for Promises.

📦 Installation

Install Typer via npm:

npm install @illavv/run_typer

🔧 Usage Examples

✅ Basic Type Checking

import Typer from '@illavv/run_typer';

console.log(Typer.is("Hello", "string")); // true
console.log(Typer.is(123, "number")); // true
console.log(Typer.is(true, "boolean")); // true
console.log(Typer.is([], "array")); // true
console.log(Typer.is({}, "object")); // true

🏗 Validating Object Structures

You can define an expected schema and validate an object against it:

const schema = {
    name: "string",
    age: "number",
    address: {
        city: "string",
        zip: "number"
    }
};

const validData = {
    name: "John",
    age: 30,
    address: {
        city: "New York",
        zip: 10001
    }
};

const invalidData = {
    name: "John",
    age: "thirty",
    address: {
        city: "New York",
        zip: "not-a-number"
    }
};

console.log(Typer.checkStructure(schema, validData).isValid); // true
console.log(Typer.checkStructure(schema, invalidData).errors); // Errors in age and zip

🛠 Registering Custom Types

Typer.registerType("positive", (value) => {
    if (typeof value !== "number" || value <= 0) {
        throw new TypeError("Value must be a positive number");
    }
    return value;
});

console.log(Typer.is(10, "positive")); // true
console.log(Typer.is(-5, "positive")); // false

🔥 Unregistering a Type

Typer.unregisterType("positive");

📜 Listing All Registered Types

console.log(Typer.listTypes());

🔍 Type Checking for Functions (Ensuring Input & Output Types)

const safeFunction = Typer.expect((x: number) => x * 2, {
    paramTypes: "number",
    returnType: "number"
});

console.log(safeFunction(4)); // 8
console.log(safeFunction("hello")); // Throws TypeError