feat: Add globalName entrypoint option.

packages/wxt-demo/src/entrypoints/background.ts

@@ -1,5 +1,6 @@
 export default defineBackground({
   // type: 'module',
+  globalName: false,
 
   main() {
     console.log(browser.runtime.id);

packages/wxt/src/core/builders/vite/index.ts

@@ -109,7 +109,6 @@ export async function createViteBuilder(
     const plugins: NonNullable<vite.UserConfig['plugins']> = [
       wxtPlugins.entrypointGroupGlobals(entrypoint),
     ];
-    const iifeReturnValueName = safeVarName(entrypoint.name);
 
     if (
       entrypoint.type === 'content-script-style' ||
@@ -118,11 +117,24 @@ export async function createViteBuilder(
       plugins.push(wxtPlugins.cssEntrypoints(entrypoint, wxtConfig));
     }
 
+    let iifeReturnValueName: string;
+    if (typeof entrypoint.options.globalName === 'string') {
+      iifeReturnValueName = entrypoint.options.globalName;
+    } else if (typeof entrypoint.options.globalName === 'function') {
+      iifeReturnValueName = entrypoint.options.globalName(entrypoint);
+    } else {
+      iifeReturnValueName = safeVarName(entrypoint.name);
+    }
+
     if (
       entrypoint.type === 'content-script' ||
       entrypoint.type === 'unlisted-script'
     ) {
-      plugins.push(wxtPlugins.iifeFooter(iifeReturnValueName));
+      if (entrypoint.options.globalName === false) {
+        plugins.push(wxtPlugins.iifeAnonymous(iifeReturnValueName));
+      } else {
+        plugins.push(wxtPlugins.iifeFooter(iifeReturnValueName));
+      }
     }
 
     return {

packages/wxt/src/core/builders/vite/plugins/iifeAnonymous.ts

@@ -0,0 +1,21 @@
+import type { Plugin } from 'vite';
+
+/**
+ * Remove the `var name = ` prefix from the generated code so it becomes an anonymous IIFE.
+ * Handle both minified and non-minified cases.
+ */
+export function iifeAnonymous(iifeReturnValueName: string): Plugin {
+  return {
+    name: 'wxt:iife-anonymous',
+    generateBundle(_, bundle) {
+      for (const chunk of Object.values(bundle)) {
+        if (chunk.type === 'chunk' && chunk.isEntry) {
+          const namedIIFEPrefix = new RegExp(
+            `^var ${iifeReturnValueName}\\s*=\\s*(\\(function)`,
+          );
+          chunk.code = chunk.code.replace(namedIIFEPrefix, '$1');
+        }
+      }
+    },
+  };
+}

packages/wxt/src/core/builders/vite/plugins/index.ts

@@ -14,3 +14,4 @@ export * from './removeEntrypointMainFunction';
 export * from './wxtPluginLoader';
 export * from './resolveAppConfig';
 export * from './iifeFooter';
+export * from './iifeAnonymous';

packages/wxt/src/core/utils/building/find-entrypoints.ts

@@ -342,6 +342,7 @@ async function getUnlistedScriptEntrypoint(
       {
         include: options.include,
         exclude: options.exclude,
+        globalName: options.globalName,
       },
       wxt.config.browser,
     ),

packages/wxt/src/types.ts

@@ -551,6 +551,25 @@ export interface BaseEntrypointOptions {
    * @default undefined
    */
   exclude?: TargetBrowser[];
+  /**
+   * The variable name for the IIFE in the JS output bundle.
+   *
+   * This option is for content scripts with world=MAIN, and unlisted scripts.
+   * It's relevant for scripts that are inserted into the page context where the default IIFE
+   * variable name may conflict with an existing variable on the target page. This applies to content
+   * scripts with world=MAIN, and others, such as unlisted scripts, that could be dynamically injected
+   * into the page with a <script> tag.
+   *
+   * Available options:
+   * - `true`: automatically generate a name for the IIFE based on the entrypoint name
+   * - `false`: Output the IIFE without a variable name, making it anonymous. This is the safest option
+   *  to avoid conflicts with existing variables on the page. This will become the default in a future version of WXT.
+   * - `string`: Use the provided string as the global variable name.
+   * - `function`: A function that receives the entrypoint and returns a string to use as the variable name.
+   *
+   * @default true
+   */
+  globalName?: string | boolean | ((entrypoint: Entrypoint) => string);
 }
 
 export interface BackgroundEntrypointOptions extends BaseEntrypointOptions {