Jsonify: Add jump to definition and any support (#519)

Co-authored-by: Michaël De Boey <info@michaeldeboey.be>
Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

source/internal.d.ts

@@ -1,4 +1,5 @@
 import type {Primitive} from './primitive';
+import type {Simplify} from './simplify';
 
 /**
 Returns a boolean for whether the two given types are equal.
@@ -108,3 +109,78 @@ export type IsUpperCase<T extends string> = T extends Uppercase<T> ? true : fals
 Returns a boolean for whether the string is numeric.
 */
 export type IsNumeric<T extends string> = T extends `${number}` ? true : false;
+
+/**
+Returns a boolean for whether the the type is `any`.
+
+@link https://stackoverflow.com/a/49928360/1490091
+*/
+export type IsAny<T> = 0 extends 1 & T ? true : false;
+
+/**
+For an object T, if it has any properties that are a union with `undefined`, make those into optional properties instead.
+
+@example
+```
+type User = {
+	firstName: string;
+	lastName: string | undefined;
+};
+
+type OptionalizedUser = UndefinedToOptional<User>;
+//=> {
+// 	firstName: string;
+// 	lastName?: string;
+// }
+```
+*/
+export type UndefinedToOptional<T extends object> = Simplify<
+{
+	// Property is not a union with `undefined`, keep it as-is.
+	[Key in keyof Pick<T, FilterDefinedKeys<T>>]: T[Key];
+} & {
+	// Property _is_ a union with defined value. Set as optional (via `?`) and remove `undefined` from the union.
+	[Key in keyof Pick<T, FilterOptionalKeys<T>>]?: Exclude<T[Key], undefined>;
+}
+>;
+
+// Returns `never` if the key or property is not jsonable without testing whether the property is required or optional otherwise return the key.
+type BaseKeyFilter<Type, Key extends keyof Type> = Key extends symbol
+	? never
+	: Type[Key] extends symbol
+		? never
+		: [(...args: any[]) => any] extends [Type[Key]]
+			? never
+			: Key;
+
+/**
+Returns the required keys.
+*/
+type FilterDefinedKeys<T extends object> = Exclude<
+{
+	[Key in keyof T]: IsAny<T[Key]> extends true
+		? Key
+		: undefined extends T[Key]
+			? never
+			: T[Key] extends undefined
+				? never
+				: BaseKeyFilter<T, Key>;
+}[keyof T],
+undefined
+>;
+
+/**
+Returns the optional keys.
+*/
+type FilterOptionalKeys<T extends object> = Exclude<
+{
+	[Key in keyof T]: IsAny<T[Key]> extends true
+		? never
+		: undefined extends T[Key]
+			? T[Key] extends undefined
+				? never
+				: BaseKeyFilter<T, Key>
+			: never;
+}[keyof T],
+undefined
+>;

source/jsonify.d.ts

@@ -1,32 +1,26 @@
 import type {JsonPrimitive, JsonValue} from './basic';
 import type {EmptyObject} from './empty-object';
-import type {Merge} from './merge';
+import type {IsAny, UndefinedToOptional} from './internal';
 import type {NegativeInfinity, PositiveInfinity} from './numeric';
 import type {TypedArray} from './typed-array';
 
 // Note: The return value has to be `any` and not `unknown` so it can match `void`.
 type NotJsonable = ((...args: any[]) => any) | undefined | symbol;
 
-// Returns never if the key or property is not jsonable without testing whether the property is required or optional otherwise return the key.
-type BaseKeyFilter<Type, Key extends keyof Type> = Key extends symbol
-	? never
-	: Type[Key] extends symbol
-		? never
-		: [(...args: any[]) => any] extends [Type[Key]]
-			? never
-			: Key;
-
-// Returns never if the key or property is not jsonable or optional otherwise return the key.
-type RequiredKeyFilter<Type, Key extends keyof Type> = undefined extends Type[Key]
-	? never
-	: BaseKeyFilter<Type, Key>;
-
-// Returns never if the key or property is not jsonable or required otherwise return the key.
-type OptionalKeyFilter<Type, Key extends keyof Type> = undefined extends Type[Key]
-	? Type[Key] extends undefined
-		? never
-		: BaseKeyFilter<Type, Key>
-	: never;
+type JsonifyTuple<T extends [unknown, ...unknown[]]> = {
+	[Key in keyof T]: T[Key] extends NotJsonable ? null : Jsonify<T[Key]>;
+};
+
+type FilterJsonableKeys<T extends object> = {
+	[Key in keyof T]: T[Key] extends NotJsonable ? never : Key;
+}[keyof T];
+
+/**
+JSON serialize objects (not including arrays) and classes.
+*/
+type JsonifyObject<T extends object> = {
+	[Key in keyof Pick<T, FilterJsonableKeys<T>>]: Jsonify<T[Key]>;
+};
 
 /**
 Transform a type to one that is assignable to the `JsonValue` type.
@@ -85,29 +79,36 @@ const timeJson = JSON.parse(JSON.stringify(time)) as Jsonify<typeof time>;
 
 @category JSON
 */
-export type Jsonify<T> =
-	// Check if there are any non-JSONable types represented in the union.
-	// Note: The use of tuples in this first condition side-steps distributive conditional types
-	// (see https://github.com/microsoft/TypeScript/issues/29368#issuecomment-453529532)
-	[Extract<T, NotJsonable | bigint>] extends [never]
-		? T extends PositiveInfinity | NegativeInfinity	? null
-			: T extends JsonPrimitive ? T // Primitive is acceptable
-				: T extends object
-				// Any object with toJSON is special case
-					? T extends {toJSON(): infer J} ? (() => J) extends (() => JsonValue) // Is J assignable to JsonValue?
-						? J // Then T is Jsonable and its Jsonable value is J
-						: Jsonify<J> // Maybe if we look a level deeper we'll find a JsonValue
-					// Instanced primitives are objects
-						: T extends Number ? number
-							: T extends String ? string
-								: T extends Boolean ? boolean
-									: T extends Map<any, any> | Set<any> ? EmptyObject
-										: T extends TypedArray ? Record<string, number>
-											: T extends any[]
-												? {[I in keyof T]: T[I] extends NotJsonable ? null : Jsonify<T[I]>}
-												: Merge<
-												{[Key in keyof T as RequiredKeyFilter<T, Key>]: Jsonify<T[Key]>},
-												{[Key in keyof T as OptionalKeyFilter<T, Key>]?: Jsonify<Exclude<T[Key], undefined>>}
-												> // Recursive call for its children
-					: never // Otherwise any other non-object is removed
-		: never; // Otherwise non-JSONable type union was found not empty
+export type Jsonify<T> = IsAny<T> extends true
+	? any
+	: T extends PositiveInfinity | NegativeInfinity
+		? null
+		: T extends JsonPrimitive
+			? T
+			: // Instanced primitives are objects
+			T extends Number
+				? number
+				: T extends String
+					? string
+					: T extends Boolean
+						? boolean
+						: T extends Map<any, any> | Set<any>
+							? EmptyObject
+							: T extends TypedArray
+								? Record<string, number>
+								: T extends NotJsonable
+									? never // Non-JSONable type union was found not empty
+									: // Any object with toJSON is special case
+									T extends {toJSON(): infer J}
+										? (() => J) extends () => JsonValue // Is J assignable to JsonValue?
+											? J // Then T is Jsonable and its Jsonable value is J
+											: Jsonify<J> // Maybe if we look a level deeper we'll find a JsonValue
+										: T extends []
+											? []
+											: T extends [unknown, ...unknown[]]
+												? JsonifyTuple<T>
+												: T extends ReadonlyArray<infer U>
+													? Array<U extends NotJsonable ? null : Jsonify<U>>
+													: T extends object
+														? JsonifyObject<UndefinedToOptional<T>> // JsonifyObject recursive call for its children
+														: never; // Otherwise any other non-object is removed

source/set-return-type.d.ts

@@ -1,4 +1,5 @@
-type IsAny<T> = 0 extends (1 & T) ? true : false; // https://stackoverflow.com/a/49928360/3406963
+import type {IsAny} from './internal';
+
 type IsNever<T> = [T] extends [never] ? true : false;
 type IsUnknown<T> = IsNever<T> extends false ? T extends unknown ? unknown extends T ? IsAny<T> extends false ? true : false : false : false : false;
 

test-d/jsonify.ts

@@ -312,3 +312,13 @@ type ExpectedAppDataJson = {
 declare const response: Jsonify<AppData>;
 
 expectType<ExpectedAppDataJson>(response);
+
+expectType<any>({} as Jsonify<any>);
+
+declare const objectWithAnyProperty: Jsonify<{
+	a: any;
+}>;
+expectType<{a: any}>(objectWithAnyProperty);
+
+declare const objectWithAnyProperties: Jsonify<Record<string, any>>;
+expectType<Record<string, any>>(objectWithAnyProperties);