Make esm support optional

src/Options.ts

@@ -11,6 +11,7 @@ export interface RunOptions {
 export interface ProjectConfig {
   ignore: string[];
   swc?: SwcConfig;
+  esm?: boolean;
   extensions: string[];
   cacheDir: string;
 }

src/Supervisor.ts

@@ -1,6 +1,7 @@
 import type { ChildProcess, StdioOptions } from "child_process";
 import { spawn } from "child_process";
 import { EventEmitter, once } from "events";
+import { defaultTo } from "lodash";
 import { setTimeout } from "timers/promises";
 import type { RunOptions } from "./Options.js";
 import type { Project } from "./Project.js";
@@ -66,6 +67,7 @@ export class Supervisor extends EventEmitter {
         ...process.env,
         WDS_SOCKET_PATH: this.socketPath,
         WDS_EXTENSIONS: this.project.config.extensions.join(","),
+        WDS_ESM_ENABLED: defaultTo(this.project.config.esm, true) ? "true" : "false",
       },
       stdio: stdio,
       detached: true,

src/hooks/child-process-register.ts

@@ -15,5 +15,7 @@ process.setSourceMapsEnabled(true);
 // register the CJS hook to intercept require calls the old way
 import "./child-process-cjs-hook.cjs";
 
-// register the ESM loader the new way
-register("./child-process-esm-loader.js", import.meta.url);
+if (process.env.WDS_ESM_ENABLED === "true") {
+  // register the ESM loader the new way
+  register("./child-process-esm-loader.js", import.meta.url);
+}