Added tests for JSONL + related fixes.

src/jsonl/parser.d.ts

@@ -1,10 +1,16 @@
+/// <reference types="node" />
+
+import {Buffer} from 'node:buffer';
+
 export = parser;
 
 interface OutputItem {
   key: number;
-  value: unknown;
+  value: any;
 }
 
 type Reviver = (this: unknown, key: string, value: unknown) => unknown;
 
-declare function parser(reviver?: Reviver): AsyncIterableIterator<OutputItem>;
+declare function parser(
+  reviver?: Reviver
+): (x: string | Buffer) => AsyncGenerator<OutputItem, void, unknown>;

src/jsonl/parserStream.d.ts

@@ -9,4 +9,6 @@ interface ParserOptions extends DuplexOptions {
   reviver?: (this: unknown, key: string, value: unknown) => unknown;
 }
 
-declare function parserStream<T>(options: ParserOptions): TypedDuplex<string | Uint8Array, T>;
+declare function parserStream<T = any>(
+  options?: ParserOptions
+): TypedDuplex<string | Uint8Array, T>;

src/jsonl/stringerStream.d.ts

@@ -14,4 +14,4 @@ interface StringerOptions {
   space?: string | number;
 }
 
-declare function stringer<T>(options: any): TypedTransform<T, string>;
+declare function stringer<T>(options?: any): TypedTransform<T, string>;

ts-check/json.ts

@@ -0,0 +1,27 @@
+import chain, {type Arg0, type Ret, type ChainItem} from 'stream-chain';
+
+import parser from 'stream-chain/jsonl/parser.js';
+import parserStream from 'stream-chain/jsonl/parserStream.js';
+import stringerStream from 'stream-chain/jsonl/stringerStream.js';
+
+import fs, { createReadStream, createWriteStream } from 'node:fs';
+
+const pipeline1 = chain([
+  createReadStream('input.json'),
+  parser(),
+  ({value}: {value: number}) => value + 1,
+  stringerStream(),
+  createWriteStream('output.json')
+] as const);
+
+void pipeline1;
+
+const pipeline2 = chain([
+  createReadStream('input.json'),
+  parserStream(),
+  ({value}: {value: number}) => value + 1,
+  stringerStream(),
+  createWriteStream('output.json')
+] as const);
+
+void pipeline2;