Module
λ "Functions all the way down" data validation for JavaScript and TypeScript.
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export type Validator<ValidType = unknown, Err = unknown> = (( value: unknown, ...parents: any[]) => Err | undefined) & ValidatorTypeMeta<ValidType>;
export type StructValidator< ValidType = unknown, Err extends IStructure = any> = ((value: unknown, ...parents: any[]) => Err) & ValidatorTypeMeta<ValidType>;
export type ExtractErr<V extends Validator<any, any>> = Exclude< ReturnType<V>, undefined>;
// `__typeMeta` is a compile-time only property used to `Infer` the valid type definition.// It's optional so that the type accurately describes runtime validators which won't have// a property called `__typeMeta` and it's nested so we can infer `undefined` correctly.// https://stackoverflow.com/questions/72402413/is-it-possible-to-make-a-property-required-yet-preserve-undefinedexport type ValidatorTypeMeta<ValidType> = { readonly __typeMeta?: { readonly validType: ValidType };};
// Infer<Validator<Error, string>> // string// Infer<Validator<Error, string | undefined>> // string | undefinedexport type Infer<V extends Validator<any, any>> = Exclude< V['__typeMeta'], undefined>['validType'];
// Changes the valid type meta e.g.// const validator: Validator<unknown, Error> = (value) => new Error('Invalid');// const annotatedValidator = annotate<number>()(validator); // Validator<number, Error>// type ValidType = Infer<typeof annotatedValidator>; // number// https://medium.com/@nandin-borjigin/partial-type-argument-inference-in-typescript-and-workarounds-for-it-d7c772788b2eexport const annotate = <ValidType>() => <V extends Validator<any, any>>( validator: V ): Validator<ValidType, ExtractErr<ReturnType<V>>> => validator;
export interface ErrItem<Err> { readonly path: string; readonly err: Err;}
export const listErrors = <Err>(err: any) => { // Everything other than `undefined` is considered an error const _isError = (value: unknown) => // NOTE: We're reserving `Promise` to add async support in the future. typeof value !== 'undefined' && !(value instanceof Promise);
const _listErrors = (err: any, path: string = ''): ErrItem<Err>[] => { if (isIStructure(err)) { return ownEnumerableEntries( err as { [key: string | symbol]: any } ).flatMap(([key, value]) => _listErrors(value, path ? `${path}.${String(key)}` : String(key)) ); } return _isError(err) ? [{ path, err: isIError(err) ? err.toPrimitiveError() : err }] : []; };
return _listErrors(err);};
// We expose `isError` and `hasError` as both verbs can make sense depending on context// i.e. some validators return 1 error, some return many.export const isError = <Err>(err: Err): err is Exclude<Err, undefined> => !!listErrors(err).length;export const hasError = isError;
export interface AssertErrParams<Err> { readonly error: Err; readonly errorList: ErrItem<unknown>[];}
export function assert<V extends Validator>( value: unknown, validator: V, logValue?: true): asserts value is Infer<V>;export function assert<V extends Validator>( value: unknown, validator: V, message: string): asserts value is Infer<V>;export function assert<V extends Validator>( value: unknown, validator: V, error: Error): asserts value is Infer<V>;export function assert<V extends Validator>( value: unknown, validator: V, createError: (params: AssertErrParams<ExtractErr<V>>) => Error | string): asserts value is Infer<V>;export function assert<V extends Validator>( value: any, validator: V, err?: any) { const error = validator(value); const errorList = listErrors(error); if (!errorList.length) { return; } if (typeof err === 'undefined' || err === true) { throw new AssertError(errorList, err ? value : undefined); } const result = typeof err === 'function' ? err({ error: error, errorList }) : err; throw typeof result === 'string' ? new Error(result) : result;}
const ONE_SIDED = Symbol.for('ok-computer.one-sided');
type OneSided<T> = T & { readonly [ONE_SIDED]?: void;};
export const okay = <V extends Validator>( value: unknown, validator: V // HACK: Err on the side of caution with a "one sided" type guard as in many cases it's // unsound to infer the negative case from a validator. // https://stackoverflow.com/a/73513991/607471 // https://github.com/microsoft/TypeScript/issues/15048#issuecomment-534376266 // https://www.typescriptlang.org/play?#code/PTAEAsBdIBwZwFwjpAhgYwNYHsBuBTAJwDMAbbAdwDp1sBbYARwFd8UBLbAOzmAHYAzAFYAjAAYAHACY+wSAE8Y+ALQBzZqkIATZcx7Y9W0vOVdNhSnF1dOXZQqXL2d-KTgqARoVRd04ALAAUEG0PJCg7HAAyuDYhJBRkITOqqAAvKAAFLiopKwIoD7yAJQFOXn4EXCgKMlcqWkAfKAA3kGgoIT4kMyEXKAO+NjEoOWs6WkZAOS1KVOgAGQLo7msVKT49ZDgoAA8oOIA3EEAvkFBIKAAQqhaIdwooMRcIulZY-gFs-WgAD6gXGYdA8RGK6WabUCHQiI0ykRicQSSRS2VW+GKYMh0Ohl0AoOSgADCcS66EgxgB5ko+C0A2wNWR9Xa2M63V6-Q+VGRdEyxWOUI6J1ArncrSZ2MugBlyUAASV8xPwpPJZkIFgo1NpoAABoDgURNVkACrgSKgWjMUg0jikUigEGFel1VIUdjbUAbLY7fbiYpi6FdHp9FYVTnYACiAA8YNxNpB2LkeXzoWdAsmLmAAOLYbB3QKhR7PKRvVEVL4M1L-HUgwhgpqi-kwrKDYZB8aTabfVTzJYt-DrTaqV3Nb115mgPGE+WK+QUlVUmmQOmajua30df1snuc5Lc3liwXCypY5njokqhVk6ddOioZzVJdlv4AoFVlf1v2swMchcRqNcGNx0gEzHMBQ1nQg91OIIgA // NOTE: This isn't necessary for `assert` because, in terms of control flow, it only // exposes a positive case.): value is OneSided<Infer<V>> => { if (isError(validator(value))) { return false; } return true;};
export const withErr = <Err, V extends Validator<any, any>>( validator: V, err: Err ): Validator<Infer<V>, Err> => (value: unknown, ...parents: any[]) => isError(validator(value, ...parents)) ? err : undefined;export const err = withErr;
export const INTROSPECT = Symbol.for('ok-computer.introspect');
export const create = <ValidType>(predicate: (value: unknown, ...parents: any[]) => boolean) => <Err>(err: Err): Validator<ValidType, Err> => (value, ...parents) => value === INTROSPECT || !predicate(value, ...parents) ? err : undefined;
const introspectValidator = <Err>(validator: Validator<unknown, Err>) => { const error = validator(INTROSPECT); if (!isError(error)) { throw new Error('Validator introspection failed'); } return error;};
export const is = <ValidType>(value: ValidType) => create<ValidType>((actual) => actual === value)(`Expected ${String(value)}`);
export const typeOf = <ValidType>(str: string) => create<ValidType>((value) => typeof value === str)(`Expected typeof ${str}`);
export const instanceOf = <T>(ctor: { new (...args: any[]): T }) => create<T>((value) => value instanceof ctor)( `Expected instanceof ${ctor.name}` );
export const number = typeOf<number>('number');
export const boolean = typeOf<boolean>('boolean');
export const bigint = typeOf<bigint>('bigint');
export const string = typeOf<string>('string');
export const symbol = typeOf<symbol>('symbol');
export const fn = typeOf<Function>('function');
export const undef = typeOf<undefined>('undefined');
export const nul = is(null);
export const integer = create<number>(Number.isInteger)('Expected integer');
export const finite = create<number>(Number.isFinite)('Expected finite number');
type ArrReturnTypes<T extends ((...args: any) => any)[]> = { [I in keyof T]: ReturnType<T[I] extends (...args: any) => any ? T[I] : never>;};
export const or = <V extends Validator<any, any>[]>( ...validators: V): Validator< Infer<V[number]>, ORError<Exclude<ArrReturnTypes<V>[number], undefined>[]>> => { const error = new ORError( validators.map((validator) => introspectValidator<ArrReturnTypes<V>[number]>(validator) ) ); return create((value, ...parents) => validators.some((validator) => !isError(validator(value, ...parents))) )(error);};
export const xor = <V extends Validator<any, any>[]>( ...validators: V): Validator< Infer<V[number]>, XORError<Exclude<ArrReturnTypes<V>[number], undefined>[]>> => { const error = new XORError( validators.map((validator) => introspectValidator<ArrReturnTypes<V>[number]>(validator) ) ); return create((value, ...parents) => { const passes = validators.reduce<boolean[]>((acc, validator, i) => { if (acc.length < 2) { const error = validator(value, ...parents); if (!isError(error)) { acc.push(true); } } return acc; }, []); return passes.length === 1; })(error);};
export const and = <V extends Validator<any, any>[]>( ...validators: V): Validator< Infer<V[0]>, ANDError<Exclude<ArrReturnTypes<V>[number], undefined>[]>> => { const error = new ANDError( validators.map((validator) => introspectValidator<ArrReturnTypes<V>[number]>(validator) ) ); return create((value, ...parents) => validators.every((validator) => !isError(validator(value, ...parents))) )(error);};
// I suspect `array(string)` is going to be more commonly used as most of// the time you care what is in the array... but this is basically a patch// on the fact `instanceOf(Array)` isn't reliable.// It could in theory be written as `array(create(() => true))` but that'd// return `asStructure(['Expected array'])` err which probably isn't ideal.export const arr = create<unknown[]>(Array.isArray)('Expected array');
export const maxLength = (len: number) => err( and( or(string, arr), create((value) => (value as any[] | string).length <= len)('Invalid') ), `Expected max length ${len}` );
export const minLength = (len: number) => err( and( or(string, arr), create((value) => (value as any[] | string).length >= len)('Invalid') ), `Expected min length ${len}` );
export const length = (min: number, max: number = min) => err( and(minLength(min), maxLength(max)), min === max ? `Expected length ${min}` : `Expected length between ${min} and ${max}` );
export const min = (num: number) => err( and(number, create((value) => (value as number) >= num)('Invalid')), `Expected min ${num}` );
export const max = (num: number) => err( and(number, create((value) => (value as number) <= num)('Invalid')), `Expected max ${num}` );
export const nullish = err(or(undef, nul), 'Expected nullish');
export const includes = (value: any) => err( and( or(arr, string), create((actual) => (actual as string | any[]).includes(value))('Invalid') ), `Expected to include ${value}` );
export const pattern = (regex: RegExp) => err( and(string, create((value) => regex.test(value as string))('Invalid')), `Expected to match pattern ${regex}` );
export const oneOf = <T extends any[]>(...allowed: T) => err( or(...allowed.map((val) => is<T[number]>(val))), `Expected one of ${allowed.join(', ')}` );
export const not = <ValidType, Err>( validator: Validator<unknown, Err>): Validator<ValidType, NegateError<Err>> => create<ValidType>((value, ...parents) => isError(validator(value, ...parents)) )(new NegateError(introspectValidator(validator)));
export type ArrayErrorStruct<V extends Validator<any, any>> = ( | ExtractErr<V> | string | undefined)[] & IStructure;
export const array = <V extends Validator<any, any>>( validator: V ): StructValidator<Infer<V>[], ArrayErrorStruct<V>> => (value, ...parents) => { if (value === INTROSPECT) { const err: ArrayErrorStruct<V> = asStructure([ introspectValidator(validator) ]); return err; } if (!Array.isArray(value)) { // NOTE: We could alternatively add an enumerable root symbol to the // structural array (like `object`) which means the return value could be // `Err | undefined` rather than `Err | string | undefined`. const err: ArrayErrorStruct<V> = asStructure(['Expected array']); return err; } const err: ArrayErrorStruct<V> = asStructure( value.map((val) => validator(val, value, ...parents)) ); return err; };
export type TupleErrorStruct<V extends Validator<any, any>[]> = Exclude< ArrReturnTypes<V>[number] | string, undefined>[] & IStructure;
// TODO: Figure out how to Infer a tuple type, i.e.// Infer<typeof tuple(string, number, boolean)> // (string | number | boolean)[] ❌// Infer<typeof tuple(string, number, boolean)> // [string, number, boolean] ✅// (I've tried a few ideas from GitHub / StackOverflow but `boolean` is incorrectly expanded to [true, false] 🤔)// https://stackoverflow.com/questions/69571110/how-to-turn-union-into-a-tuple-in-typescript// https://github.com/microsoft/TypeScript/issues/13298#issuecomment-885980381export const tuple = <V extends Validator<any, any>[]>( ...validators: V): StructValidator<Infer<V[number]>[], TupleErrorStruct<V>> => { if (validators.length < 1) { throw new Error('tuple requires as least 1 validator'); } return (value, ...parents) => { if (value === INTROSPECT || !Array.isArray(value)) { return asStructure( validators.map((validator) => introspectValidator<ArrReturnTypes<V>[number]>(validator) ) ); } const count = Math.max(validators.length, value.length); return asStructure( new Array(count).fill(null).map((_, i) => { const validator = validators[i]; const val = value[i]; const indexExists = i in value; return validator ? indexExists ? validator(val, value, ...parents) : introspectValidator(validator) : 'Extraneous element'; }) ); };};
// Like `and` but error only includes failing clauses and doesn't short circuit evaluation (good for password// validation UIs or stacked error messages)export const all = <V extends Validator<any, any>[]>( ...validators: V): Validator< Infer<V[0]>, ANDError<Exclude<ArrReturnTypes<V>[number], undefined>[]>> => { return (value, ...parents) => { if (value === INTROSPECT) { return new ANDError( validators.map((validator) => introspectValidator<ArrReturnTypes<V>[number]>(validator) ) ); } const errors = validators .map((validator) => validator(value, ...parents)) .filter((val): val is Exclude<ArrReturnTypes<V>[number], undefined> => isError(val) ); return errors.length ? new ANDError(errors) : undefined; };};
type ObjReturnTypes<T extends Record<keyof T, (...a: any[]) => any>> = { [P in keyof T]: ReturnType<T[P]>;};
export const OBJECT_ROOT = Symbol.for('ok-computer.object-root');
export type ObjectErrorStruct< Validators extends Record<any, (...a: any[]) => any>> = ObjReturnTypes<Validators> & { [OBJECT_ROOT]?: string;} & IStructure;
type _InferObject<T extends Record<any, (val: any, ...parents: any[]) => any>> = { [P in keyof T]: T[P] extends Validator<any, any> ? Infer<T[P]> : never; };type InferObject<T extends Record<any, (val: any, ...parents: any[]) => any>> = SelectivePartial<_InferObject<T>, keyof UndefinedProps<_InferObject<T>>>;
export const object = < Validators extends Record< keyof Validators, (val: any, ...parents: any[]) => any > >( validators: Validators, { allowUnknown = false }: { allowUnknown?: boolean } = {} ): StructValidator<InferObject<Validators>, ObjectErrorStruct<Validators>> => (...parents: unknown[]) => { const values = parents[0]; const introspecting = values === INTROSPECT; const ret = asStructure( {} as ObjReturnTypes<Validators> & { [OBJECT_ROOT]?: string; } ); if (introspecting || !isPlainObject(values)) { ret[OBJECT_ROOT] = 'Expected object'; } else if (!allowUnknown) { const expectedKeys = Object.keys(validators); const actualKeys = Object.keys(values); const unknownKeys = actualKeys.filter( (key) => !expectedKeys.includes(key) ); if (unknownKeys.length) { ret[OBJECT_ROOT] = `Unknown properties ${unknownKeys .map((key) => `"${key}"`) .join(', ')}`; } } return ownEnumerableEntries(validators).reduce< ObjReturnTypes<Validators> & IStructure >((errors, [key, validator]) => { if (typeof validator !== 'function') { throw new Error(`Expected validator to be function ${String(key)}`); } const value = introspecting ? INTROSPECT : ((values || {}) as any)[key]; const error = introspecting ? // thi doesn't use INTROSPECT so why is it here? introspectValidator(validator as Validator) : validator(value, ...parents); (errors as any)[key] = error; return errors; }, ret); };
export function merge<ValidType, Err extends IStructure>( validator: Validator<ValidType, Err>): StructValidator<ValidType, Err>;export function merge< ValidType1, ValidType2, Err1 extends IStructure, Err2 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>): StructValidator<ValidType1 & ValidType2, Err1 & Err2>;export function merge< ValidType1, ValidType2, ValidType3, Err1 extends IStructure, Err2 extends IStructure, Err3 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>, validator3: Validator<ValidType3, Err3>): StructValidator<ValidType1 & ValidType2 & ValidType3, Err1 & Err2 & Err3>;export function merge< ValidType1, ValidType2, ValidType3, ValidType4, Err1 extends IStructure, Err2 extends IStructure, Err3 extends IStructure, Err4 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>, validator3: Validator<ValidType3, Err3>, validator4: Validator<ValidType4, Err4>): StructValidator< ValidType1 & ValidType2 & ValidType3 & ValidType4, Err1 & Err2 & Err3 & Err4>;export function merge< ValidType1, ValidType2, ValidType3, ValidType4, ValidType5, Err1 extends IStructure, Err2 extends IStructure, Err3 extends IStructure, Err4 extends IStructure, Err5 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>, validator3: Validator<ValidType3, Err3>, validator4: Validator<ValidType4, Err4>, validator5: Validator<ValidType5, Err5>): StructValidator< ValidType1 & ValidType2 & ValidType3 & ValidType4 & ValidType5, Err1 & Err2 & Err3 & Err4 & Err5>;export function merge< ValidType1, ValidType2, ValidType3, ValidType4, ValidType5, ValidType6, Err1 extends IStructure, Err2 extends IStructure, Err3 extends IStructure, Err4 extends IStructure, Err5 extends IStructure, Err6 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>, validator3: Validator<ValidType3, Err3>, validator4: Validator<ValidType4, Err4>, validator5: Validator<ValidType5, Err5>, validator6: Validator<ValidType6, Err6>): StructValidator< ValidType1 & ValidType2 & ValidType3 & ValidType4 & ValidType5 & ValidType6, Err1 & Err2 & Err3 & Err4 & Err5 & Err6>;export function merge< ValidType1, ValidType2, ValidType3, ValidType4, ValidType5, ValidType6, ValidType7, Err1 extends IStructure, Err2 extends IStructure, Err3 extends IStructure, Err4 extends IStructure, Err5 extends IStructure, Err6 extends IStructure, Err7 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>, validator3: Validator<ValidType3, Err3>, validator4: Validator<ValidType4, Err4>, validator5: Validator<ValidType5, Err5>, validator6: Validator<ValidType6, Err6>, validator7: Validator<ValidType7, Err7>): StructValidator< ValidType1 & ValidType2 & ValidType3 & ValidType4 & ValidType5 & ValidType6 & ValidType7, Err1 & Err2 & Err3 & Err4 & Err5 & Err6 & Err7>;export function merge< ValidType1, ValidType2, ValidType3, ValidType4, ValidType5, ValidType6, ValidType7, ValidType8, Err1 extends IStructure, Err2 extends IStructure, Err3 extends IStructure, Err4 extends IStructure, Err5 extends IStructure, Err6 extends IStructure, Err7 extends IStructure, Err8 extends IStructure>( validator1: Validator<ValidType1, Err1>, validator2: Validator<ValidType2, Err2>, validator3: Validator<ValidType3, Err3>, validator4: Validator<ValidType4, Err4>, validator5: Validator<ValidType5, Err5>, validator6: Validator<ValidType6, Err6>, validator7: Validator<ValidType7, Err7>, validator8: Validator<ValidType8, Err8>): StructValidator< ValidType1 & ValidType2 & ValidType3 & ValidType4 & ValidType5 & ValidType6 & ValidType7 & ValidType8, Err1 & Err2 & Err3 & Err4 & Err5 & Err6 & Err7 & Err8>;export function merge(...validators: any[]): any { return (value: unknown, ...parents: any[]) => { const errors = validators .map((validator) => validator(value, ...parents)) .filter((val) => isError(val)); return asStructure(Object.assign({}, ...errors)); };}
export const when = (predicate: (value: unknown, ...parents: any[]) => boolean) => <ValidType, Err>(validator: Validator<ValidType, Err>) => create<ValidType>( (value, ...parents) => !predicate(value, ...parents) || !isError(validator(value, ...parents)) )(introspectValidator(validator));
export const match = (key: string) => create((value, parent) => parent != null && parent[key] === value)( `Expected to match ${key}` );
export const email = err( pattern( /^(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])$/i ), 'Expected email');
export const peer = (key: string) => <Err>( validator: Validator<unknown, Err> ): Validator<unknown, PeerError<Err>> => (value, ...parents) => { if (value === INTROSPECT) { return new PeerError(key, introspectValidator(validator)); } const err = validator(parents[0] && parents[0][key], ...parents); return isError(err) ? new PeerError(key, err as Err) : undefined; };
export const andPeers = (...keys: string[]) => or( and(nullish, ...keys.map((key) => peer(key)(nullish))), and(not(nullish), ...keys.map((key) => peer(key)(not(nullish)))) );export const andPeer = (key: string) => andPeers(key);
export const nandPeers = (...keys: string[]) => or( and(nullish, ...keys.map((key) => peer(key)(nullish))), not(and(not(nullish), ...keys.map((key) => peer(key)(not(nullish))))) );export const nandPeer = (key: string) => nandPeers(key);
export const orPeers = (...keys: string[]) => or(not(nullish), ...keys.map((key) => peer(key)(not(nullish))));export const orPeer = (key: string) => orPeers(key);
export const xorPeers = (...keys: string[]) => xor(not(nullish), ...keys.map((key) => peer(key)(not(nullish))));export const xorPeer = (key: string) => xorPeers(key);
export const oxorPeers = (...keys: string[]) => or( and(nullish, ...keys.map((key) => peer(key)(nullish))), xor(not(nullish), ...keys.map((key) => peer(key)(not(nullish)))) );export const oxorPeer = (key: string) => oxorPeers(key);
// `exists` is an alias for `not(nullish)` with a more accurate valid type.// Allows `okay` and `assert` to infer the positive case without a specific validator, e.g.// const fn = (foo?: { id: string }) => {// assert(foo, exists);// foo.id.startsWith('bar');// };// It allows ok computers' `assert` fn to handle the common assert case provided by node et al.export const exists = not<{}, ExtractErr<typeof nullish>>(nullish);
export const truthy = create<{}>((value) => !!value)('Expected truthy value');
export type Falsy = false | null | undefined | '' | number; // `number` covers `0` and `NaN`export const falsy = create<Falsy>((value) => !value)('Expected falsy value');