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Types Module (node-yalc/types)

The Types module provides advanced, globally available TypeScript utility types used extensively throughout the Ferrox-Node Framework to enforce extreme type safety and strict compiler checks.

Overview​

TypeScript's standard library is powerful, but enterprise frameworks require more restrictive typing to prevent developer errors (like passing an object with extra, un-typed properties to a generic function).

Key Utilities Exported​

  • Exact<T, U>: TypeScript is structurally typed, meaning an object U can have extra properties not defined in T and still be accepted. Exact enforces that U has only the properties defined in T and nothing more.
  • CompareStrict<A, B>: Checks if type A is exactly equal to type B.
  • NoExtraProperties<T, U>: Strips away any properties in U that are not present in the base type T.
  • XOR<T, U>: Enforces an exclusive OR relationship between two types. A value must match exactly T or exactly U, but never a combination of both.
  • Spread<L, R>: Strictly types the result of object spreading { ...L, ...R }, correctly handling optional properties and overwriting.
  • ClassType<T>: Represents a constructable class, heavily used in the Dependency Injection and Lifecycle hooks.
  • DeepWritable<T>: Recursively removes readonly modifiers from all nested properties of T.

Usage​

These types are exported and can be used directly in your business logic.

import { Exact, XOR } from '@node-yalc/types';

// Enforce strict object shapes
function updateConfig<T>(config: Exact<ConfigSchema, T>) {
  // config cannot contain properties not in ConfigSchema
}