Add Node compatibility to gz.js.

Node has a built-in zlib library we can just use.

This also changes the webpack config to tell it that it we don't need
this library when building for the browser. Without this change, the
build fails because Webpack wants to know explicitly what, if anything,
it should shim the library with.

Author: mstange

src/utils/gz.ts

@@ -31,6 +31,20 @@ export async function compress(
   data: string | Uint8Array,
   compressionLevel?: number
 ): Promise<Uint8Array<ArrayBuffer>> {
+  if (!(typeof window === 'object' && 'Worker' in window)) {
+    // Try to fall back to Node's zlib library.
+    const zlib = await import('zlib');
+    return new Promise((resolve, reject) => {
+      zlib.gzip(data, (errorOrNull, result) => {
+        if (errorOrNull) {
+          reject(errorOrNull);
+        } else {
+          resolve(new Uint8Array(result.buffer as ArrayBuffer));
+        }
+      });
+    });
+  }
+
   const zeeWorker = new Worker(zeeWorkerPath);
   workerOnMessage(zeeWorker);
 
@@ -55,6 +69,24 @@ export async function compress(
 
 // Neuters data's buffer, if data is a typed array.
 export async function decompress(data: Uint8Array): Promise<Uint8Array> {
+  if (!(typeof window === 'object' && 'Worker' in window)) {
+    // Handle the case where we're not running in the browser, e.g. when
+    // this code is used as part of a library in a Node project.
+    // We don't get here when running Firefox profiler tests, because our
+    // tests create a mock window with a mock Worker class.
+    // Try to fall back to Node's zlib library.
+    const zlib = await import('zlib');
+    return new Promise((resolve, reject) => {
+      zlib.gunzip(data, (errorOrNull, result) => {
+        if (errorOrNull) {
+          reject(errorOrNull);
+        } else {
+          resolve(new Uint8Array(result.buffer as ArrayBuffer));
+        }
+      });
+    });
+  }
+
   const zeeWorker = new Worker(zeeWorkerPath);
   return new Promise(function (resolve, reject) {
     workerOnMessage(zeeWorker);

webpack.config.js

@@ -32,6 +32,7 @@ const config = {
       // that Jest can profit from it too.
       'firefox-profiler-res': path.resolve(__dirname, 'res'),
     },
+    fallback: { zlib: false },
   },
   devtool: 'source-map',
   module: {