Fix(bundler): use different alias mappings based on the target. (#4163)

* Fix(bundler): use different alias mappings based on the target.
Close: #3844

* chore: reduce duplicated code.

* chore: split to two separate ComptimeStringMap.

2 files changed, 31 insertions, 0 deletions

diff --git a/test/bundler/bun-build-api.test.ts b/test/bundler/bun-build-api.test.ts
index 3b528b7be..3c2308d94 100644
--- a/test/bundler/bun-build-api.test.ts
+++ b/test/bundler/bun-build-api.test.ts
@@ -262,4 +262,32 @@ describe("Bun.build", () => {
     expect(x.logs[0].name).toBe("BuildMessage");
     expect(x.logs[0].position).toBeTruthy();
   });
+
+  test("test bun target", async () => {
+    const x = await Bun.build({
+      entrypoints: [join(import.meta.dir, "./fixtures/trivial/bundle-ws.ts")],
+      target: "bun",
+    });
+    expect(x.success).toBe(true);
+    const [blob] = x.outputs;
+    const content = await blob.text();
+
+    // use bun's ws
+    expect(content).toContain('import {WebSocket} from "ws"');
+    expect(content).not.toContain("var websocket = __toESM(require_websocket(), 1);");
+  });
+
+  test("test node target, issue #3844", async () => {
+    const x = await Bun.build({
+      entrypoints: [join(import.meta.dir, "./fixtures/trivial/bundle-ws.ts")],
+      target: "node",
+    });
+    expect(x.success).toBe(true);
+    const [blob] = x.outputs;
+    const content = await blob.text();
+
+    expect(content).not.toContain('import {WebSocket} from "ws"');
+    // depends on the ws package in the test/node_modules.
+    expect(content).toContain("var websocket = __toESM(require_websocket(), 1);");
+  });
 });
diff --git a/test/bundler/fixtures/trivial/bundle-ws.ts b/test/bundler/fixtures/trivial/bundle-ws.ts
new file mode 100644
index 000000000..0064bfdd9
--- /dev/null
+++ b/test/bundler/fixtures/trivial/bundle-ws.ts
@@ -0,0 +1,3 @@
+import { WebSocket } from "ws";
+
+console.log(WebSocket);