TypeScript Runtime Validator Typia Technical Documentation

Overview

Typia is a high-performance runtime type validation library for TypeScript. It operates solely on pure TypeScript type definitions, eliminating the need for additional schema definitions unlike other validation libraries. It offers up to 20,000 times faster performance and can perfectly validate complex union types.

Installation and Configuration

The following configuration is required in tsconfig.json:

{
  "compilerOptions": {
    "plugins": [
      {
        "transform": "typia/lib/transform"
      }
    ]
  }
}

Core Validators

Assert Validator

Purpose: Validates the type of a value and throws a TypeGuardError for incorrect types
Syntax: typia.assert<T>(input: unknown): T
Error Handling: Provides method, path, expected, and value information through TypeGuardError
Features: Allows additional properties and validates basic types and built-in classes (Date, Map, etc.)

Is Validator

Purpose: Checks if a value matches the specified type
Syntax: typia.is<T>(input: unknown): boolean
Return: Returns true if the type matches, false otherwise
Usage: Used for type checking in conditional statements

Validate Validator

Purpose: Validates value and provides detailed results
Syntax: typia.validate<T>(input: unknown): ValidationResult
Result Structure: Includes success/failure status and error information
Error Handling: Allows checking all validation errors at once

Performance Considerations

Shows up to 20,000 times faster performance compared to competing libraries like TypeBox, ajv, io-ts, zod, and class-validator
Fully supports advanced TypeScript features including complex union types, recursive types, and template literal types

Best Practices

Create reusable validation functions using createAssert, createIs, and createValidate functions
Separate instanceof checks are required for custom class validation
Function type validation requires enabling the functional setting in tsconfig.json plugin options

Integration Example

interface IMember {
  id: string & tags.Format<"uuid">;
  email: string & tags.Format<"email">;
  age: number & tags.Type<"uint32"> & tags.ExclusiveMinimum<19> & tags.Maximum<100>;
}

const assertMember = typia.createAssert<IMember>();
assertMember({
  id: "550e8400-e29b-41d4-a716-446655440000",
  email: "example@email.com",
  age: 25
});

References

Official Documentation: https://typia.io/docs/validators/assert/
Validator Documentation:
- Assert: https://typia.io/docs/validators/assert/
- Is: https://typia.io/docs/validators/is/
- Validate: https://typia.io/docs/validators/validate/

Conclusion

Typia is the optimal runtime type validation tool that ensures type safety while providing outstanding performance in TypeScript projects. It operates solely on pure TypeScript types and features comprehensive support for complex types.