Polymorphic getJson

Author: sebastianquek

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to
 ### Added
 
 - Expose `EngineName`, `EngineParameters` and `AllowArbitraryParams` types.
+- Expose `InvalidArgumentTypesError` error.
 
 ### Changed
 

mod.ts

@@ -1,7 +1,11 @@
 export type { Config } from "./src/config.ts";
 export { config } from "./src/config.ts";
 
-export { InvalidTimeoutError, MissingApiKeyError } from "./src/errors.ts";
+export {
+  InvalidArgumentTypesError,
+  InvalidTimeoutError,
+  MissingApiKeyError,
+} from "./src/errors.ts";
 
 export type {
   AccountApiParameters,

src/errors.ts

@@ -1,3 +1,10 @@
+export class InvalidArgumentTypesError extends Error {
+  constructor() {
+    super("Provide the arguments with the correct type");
+    Object.setPrototypeOf(this, InvalidArgumentTypesError.prototype);
+  }
+}
+
 export class MissingApiKeyError extends Error {
   constructor() {
     super(

src/serpapi.ts

@@ -1,3 +1,4 @@
+import { InvalidArgumentTypesError } from "./errors.ts";
 import {
   AccountApiParameters,
   AccountInformation,
@@ -69,13 +70,44 @@ const SEARCH_ARCHIVE_PATH = `/searches`;
  *   }
  * });
  */
-export async function getJson<
+export function getJson<
+  E extends EngineName = EngineName,
+  P1 extends AllowArbitraryParams<EngineParameters<E>> = EngineParameters<E>,
+  P2 extends AllowArbitraryParams<EngineParameters<E, false>> =
+    EngineParameters<E, false>,
+>(
+  ...args:
+    | [parameters: P1, callback?: (json: BaseResponse<E>) => void]
+    | [
+      engine: string, // intentionally kept as a string to support arbitrary params
+      parameters: P2,
+      callback?: (json: BaseResponse<E>) => void,
+    ]
+): Promise<BaseResponse<E>> {
+  if (
+    typeof args[0] === "string" &&
+    typeof args[1] === "object"
+  ) {
+    const [engine, parameters, callback] = args;
+    return _getJson({ ...parameters, engine: engine as E }, callback);
+  } else if (
+    typeof args[0] === "object" &&
+    (typeof args[1] === "undefined" || typeof args[1] === "function")
+  ) {
+    const [parameters, callback] = args;
+    return _getJson(parameters, callback);
+  } else {
+    throw new InvalidArgumentTypesError();
+  }
+}
+
+async function _getJson<
   E extends EngineName = EngineName,
   P extends AllowArbitraryParams<EngineParameters<E>> = EngineParameters<E>,
 >(
   parameters: P,
   callback?: (json: BaseResponse<E>) => void,
-) {
+): Promise<BaseResponse<E>> {
   const key = validateApiKey(parameters.api_key, true);
   const timeout = validateTimeout(parameters.timeout);
   const response = await _internals.execute(

src/types.ts

@@ -53,9 +53,10 @@ type AnyEngineName = string & {};
 export type EngineName = (keyof EngineMap) | AnyEngineName;
 export type EngineParameters<
   E extends EngineName = EngineName,
+  W = true, // flag for whether `engine` is a required param
 > = {
   [K in E]:
-    & { engine: K }
+    & (W extends true ? { engine: K } : { engine?: K })
     & (K extends keyof EngineMap ? EngineMap[K]["parameters"] : BaseParameters);
 }[E];