mobx-keystone/src/types/typeCheck.ts

A MobX powered state management solution based on data trees with first class support for TypeScript, snapshots, patches and much more

import { resolveTypeChecker } from "./resolveTypeChecker"
import type { AnyType, TypeToData } from "./schemas"
import type { TypeCheckError } from "./TypeCheckError"

/**
 * Checks if a value conforms to a given type.
 *
 * @template T Type.
 * @param type Type to check for.
 * @param value Value to check.
 * @returns A TypeError if the check fails or null if no error.
 */
export function typeCheck<T extends AnyType>(type: T, value: TypeToData<T>): TypeCheckError | null {
  const typeChecker = resolveTypeChecker(type)

  if (typeChecker.unchecked) {
    return null
  } else {
    return typeChecker.check(value, [], value)
  }
}