fix(js): make it compatible with rsbuild

crates/loro-wasm/scripts/bundler_patch.js

@@ -1,34 +1,69 @@
-// See https://github.com/loro-dev/loro/issues/440
-// Without this patch, Cloudflare Worker would raise issue like: "Uncaught TypeError: wasm2.__wbindgen_start is not a function"
-import * as wasm from "./loro_wasm_bg.wasm";
-import * as imports from "./loro_wasm_bg.js";
+import * as rawWasm from './loro_wasm_bg.wasm';
+import * as imports from './loro_wasm_bg.js';
 
-if (wasm.__wbindgen_start) {
-  imports.__wbg_set_wasm(wasm);
-  wasm.__wbindgen_start();
-} else if ("Bun" in globalThis) {
-  const { instance } = await WebAssembly.instantiateStreaming(
-    fetch(Bun.pathToFileURL(wasm.default)),
-    {
-      "./loro_wasm_bg.js": imports,
-    },
-  );
-  imports.__wbg_set_wasm(instance.exports);
+// Normalize how bundlers expose the wasm module/exports.
+const toModuleOrExports = (wasm) => {
+  if (!wasm) return wasm;
+  if (wasm instanceof WebAssembly.Module) return wasm;
+  if (typeof wasm === 'object' && 'default' in wasm) {
+    return wasm.default ?? wasm;
+  }
+  // rsbuild doesn't provide a default export when importing wasm.
+  return wasm;
+};
+
+const wasmModuleOrExports = toModuleOrExports(rawWasm);
 
+// Helper: ensure we end up with exports + optionally run externref init.
+const finalize = (exports) => {
+  imports.__wbg_set_wasm(exports);
+  if (typeof imports.__wbindgen_init_externref_table === 'function') {
+    imports.__wbindgen_init_externref_table();
+  }
+};
+
+if (wasmModuleOrExports && wasmModuleOrExports.__wbindgen_start) {
+  // See https://github.com/loro-dev/loro/issues/440
+  // Without this patch, Cloudflare Worker would raise issue like: "Uncaught TypeError: wasm2.__wbindgen_start is not a function"
+  // Already the initialized exports object (Cloudflare Workers path).
+  finalize(wasmModuleOrExports);
+  wasmModuleOrExports.__wbindgen_start();
+} else if ('Bun' in globalThis) {
   // Bun's wasm runtime (1.3.0 as of Oct 2025) sometimes reads externref slot 1
   // (reserved for booleans by wasm-bindgen) as the global object, causing APIs
   // like `LoroText.toDelta()` to return cyclic structures. Re-running the
   // wasm-bindgen externref table initializer after instantiation resets the
   // table so booleans stay primitives and avoids the infinite recursion seen in
   // Bun tests during `pnpm release-wasm`.
-  if (typeof imports.__wbindgen_init_externref_table === "function") {
-    imports.__wbindgen_init_externref_table();
+  let instance;
+  if (wasmModuleOrExports instanceof WebAssembly.Module) {
+    ({ instance } = await WebAssembly.instantiate(wasmModuleOrExports, {
+      './loro_wasm_bg.js': imports,
+    }));
+  } else {
+    const url = Bun.pathToFileURL(wasmModuleOrExports);
+    ({ instance } = await WebAssembly.instantiateStreaming(fetch(url), {
+      './loro_wasm_bg.js': imports,
+    }));
   }
+  finalize(instance.exports);
 } else {
-  const wkmod = await import("./loro_wasm_bg.wasm");
-  const instance = new WebAssembly.Instance(wkmod.default, {
-    "./loro_wasm_bg.js": imports,
-  });
-  imports.__wbg_set_wasm(instance.exports);
+  // Browser/node-like bundlers: either we already have exports, or a Module/URL.
+  const wkmod =
+    wasmModuleOrExports instanceof WebAssembly.Module
+      ? wasmModuleOrExports
+      : await import('./loro_wasm_bg.wasm');
+  const module =
+    wkmod instanceof WebAssembly.Module
+      ? wkmod
+      : (wkmod && wkmod.default) || wkmod;
+  const instance =
+    module instanceof WebAssembly.Instance
+      ? module
+      : new WebAssembly.Instance(module, {
+        './loro_wasm_bg.js': imports,
+      });
+  finalize(instance.exports ?? instance);
 }
-export * from "./loro_wasm_bg.js";
+
+export * from './loro_wasm_bg.js';

crates/loro-wasm/scripts/post-rollup.ts

@@ -73,45 +73,40 @@ async function rollupBase64() {
 
     const base64IndexPath = "./base64/index.js";
     const content = await Deno.readTextFile(base64IndexPath);
+    const nextContent = injectBase64WasmBranch(content, base64IndexPath);
+    await Deno.writeTextFile(base64IndexPath, nextContent);
 
-    const legacyPattern =
-        /\{\s*const wkmod = await import\('\.\/loro_wasm_bg-([^']+)\.js'\);\s*const instance = new WebAssembly\.Instance\(wkmod\.default, \{\s*"\.\/loro_wasm_bg\.js": imports,\s*\}\);\s*__wbg_set_wasm\(instance\.exports\);\s*\}/;
-    const legacyReplacement = (match: string, hash: string) => `
-import loro_wasm_bg_js from './loro_wasm_bg-${hash}.js';
-const instance = new WebAssembly.Instance(loro_wasm_bg_js(), {
-    "./loro_wasm_bg.js": imports,
-});
-__wbg_set_wasm(instance.exports);
-`;
+    await Deno.copyFile("./bundler/loro_wasm.d.ts", "./base64/loro_wasm.d.ts");
+}
 
-    const modernPattern =
-        /const wkmod = await Promise\.resolve\(\)\.then\(function \(\) { return wasm\$1; }\);\s*const instance = new WebAssembly\.Instance\(wkmod\.default, \{\s*"\.\/loro_wasm_bg\.js": imports,\s*\}\);\s*__wbg_set_wasm\(instance\.exports\);\s*/;
-    const modernReplacement = () => `const instance = loro_wasm_bg({
-    "./loro_wasm_bg.js": imports,
-});
-__wbg_set_wasm(instance.exports);
-`;
-
-    let nextContent = content;
-    let replaced = false;
-
-    if (legacyPattern.test(nextContent)) {
-        nextContent = nextContent.replace(legacyPattern, legacyReplacement);
-        replaced = true;
-    } else if (modernPattern.test(nextContent)) {
-        nextContent = nextContent.replace(modernPattern, modernReplacement);
-        replaced = true;
+function injectBase64WasmBranch(content: string, filePath: string): string {
+    const alreadyPatched =
+        content.includes("typeof wasmModuleOrExports === \"function\"");
+    if (alreadyPatched) {
+        return content;
     }
 
-    if (!replaced) {
+    const bunBranchPattern = /}\s*else if\s*\(\s*(['"])Bun\1\s+in\s+globalThis\s*\)\s*\{/;
+    if (!bunBranchPattern.test(content)) {
         throw new Error(
-            `Could not find string to replace in ${base64IndexPath}`,
+            `Could not locate Bun branch while patching ${filePath}`,
         );
     }
 
-    await Deno.writeTextFile(base64IndexPath, nextContent);
-
-    await Deno.copyFile("./bundler/loro_wasm.d.ts", "./base64/loro_wasm.d.ts");
+    const base64Branch = `} else if (typeof wasmModuleOrExports === "function") {
+  const moduleOrInstance = wasmModuleOrExports({
+    "./loro_wasm_bg.js": imports,
+  });
+  const instance =
+    moduleOrInstance instanceof WebAssembly.Instance
+      ? moduleOrInstance
+      : new WebAssembly.Instance(moduleOrInstance, {
+        "./loro_wasm_bg.js": imports,
+      });
+  finalize(instance.exports ?? instance);
+} else if ("Bun" in globalThis) {`;
+
+    return content.replace(bunBranchPattern, base64Branch);
 }
 
 async function main() {

examples/test-rsbuild/.gitignore

@@ -0,0 +1 @@
+dist/

examples/test-rsbuild/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "loro-test-rsbuild",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "rsbuild dev",
+    "build": "rsbuild build",
+    "preview": "rsbuild preview"
+  },
+  "dependencies": {
+    "loro-crdt": "link:../../crates/loro-wasm",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1"
+  },
+  "devDependencies": {
+    "@rsbuild/core": "^1.0.0",
+    "@rsbuild/plugin-react": "^1.0.0",
+    "@types/react": "^18.3.3",
+    "@types/react-dom": "^18.3.0",
+    "typescript": "^5.6.3"
+  }
+}