[pako] Explicitly reference ArrayBuffer (DefinitelyTyped#73403)

Co-authored-by: René <[email protected]>

Author: joshkel

types/pako/index.d.ts

@@ -99,46 +99,49 @@ declare namespace Pako {
 
     type Data = Uint8Array | ArrayBuffer;
 
+    // For TS <=5.6 compatibility: Uint8Array<ArrayBuffer> in TS >=5.7, Uint8Array in TS <=5.6
+    type Uint8ArrayReturnType = InstanceType<typeof Uint8Array>;
+
     /**
      * Compress data with deflate algorithm and options.
      */
-    function deflate(data: Data | string, options?: DeflateFunctionOptions): Uint8Array;
+    function deflate(data: Data | string, options?: DeflateFunctionOptions): Uint8ArrayReturnType;
 
     /**
      * The same as deflate, but creates raw data, without wrapper (header and adler32 crc).
      */
-    function deflateRaw(data: Data | string, options?: DeflateFunctionOptions): Uint8Array;
+    function deflateRaw(data: Data | string, options?: DeflateFunctionOptions): Uint8ArrayReturnType;
 
     /**
      * The same as deflate, but create gzip wrapper instead of deflate one.
      */
-    function gzip(data: Data | string, options?: DeflateFunctionOptions): Uint8Array;
+    function gzip(data: Data | string, options?: DeflateFunctionOptions): Uint8ArrayReturnType;
 
     /**
      * Decompress data with inflate/ungzip and options. Autodetect format via wrapper header
      * by default. That's why we don't provide separate ungzip method.
      */
     function inflate(data: Data, options: InflateFunctionOptions & { to: "string" }): string;
-    function inflate(data: Data, options?: InflateFunctionOptions): Uint8Array;
+    function inflate(data: Data, options?: InflateFunctionOptions): Uint8ArrayReturnType;
 
     /**
      * The same as inflate, but creates raw data, without wrapper (header and adler32 crc).
      */
     function inflateRaw(data: Data, options: InflateFunctionOptions & { to: "string" }): string;
-    function inflateRaw(data: Data, options?: InflateFunctionOptions): Uint8Array;
+    function inflateRaw(data: Data, options?: InflateFunctionOptions): Uint8ArrayReturnType;
 
     /**
      * Just shortcut to inflate, because it autodetects format by header.content. Done for convenience.
      */
     function ungzip(data: Data, options: InflateFunctionOptions & { to: "string" }): string;
-    function ungzip(data: Data, options?: InflateFunctionOptions): Uint8Array;
+    function ungzip(data: Data, options?: InflateFunctionOptions): Uint8ArrayReturnType;
 
     // https://github.com/nodeca/pako/blob/893381abcafa10fa2081ce60dae7d4d8e873a658/lib/deflate.js
     class Deflate {
         constructor(options?: DeflateOptions);
         err: ReturnCodes;
         msg: string;
-        result: Uint8Array;
+        result: Uint8ArrayReturnType;
         onData(chunk: Data): void;
         onEnd(status: number): void;
         push(data: Data | string, mode?: FlushValues | boolean): boolean;
@@ -150,7 +153,7 @@ declare namespace Pako {
         header?: Header | undefined;
         err: ReturnCodes;
         msg: string;
-        result: Uint8Array | string;
+        result: Uint8ArrayReturnType | string;
         onData(chunk: Data): void;
         onEnd(status: number): void;
         push(data: Data, mode?: FlushValues | boolean): boolean;

types/pako/pako-tests.ts

@@ -18,7 +18,8 @@ if (deflate.err !== Pako.constants.Z_OK) {
 
 console.log(deflate.result);
 
-const arr: Uint8Array = Pako.deflate("1234");
+// Ensure that the return type is narrowed correctly in TS 5.7+
+Pako.deflate("1234"); // $ExpectType Uint8Array || Uint8Array<ArrayBuffer>
 
 const data = "           ";