perf: remove browserslist-to-es-version dependency (#3585)

e2e/cases/browserslist/browserslist-config-mock/index.json

@@ -1 +1 @@
-["Chrome >= 49", "Edge >= 79", "Firefox >= 49", "Safari >= 10"]
+["Chrome >= 40", "Edge >= 79", "Firefox >= 49", "Safari >= 10"]

packages/core/package.json

@@ -65,7 +65,6 @@
     "@types/webpack-bundle-analyzer": "4.7.0",
     "@types/ws": "^8.5.12",
     "browserslist": "4.24.0",
-    "browserslist-to-es-version": "^1.0.0",
     "chokidar": "3.6.0",
     "commander": "^12.1.0",
     "connect": "3.7.0",

packages/core/src/plugins/target.ts

@@ -1,19 +1,6 @@
 import { DEFAULT_WEB_BROWSERSLIST } from '../constants';
 import type { RsbuildPlugin } from '../types';
 
-const getESVersion = async (browserslist: string[]) => {
-  const { browserslistToESVersion } = await import(
-    'browserslist-to-es-version'
-  );
-
-  // skip calculation if the browserslist is the default value
-  if (browserslist.join(',') === DEFAULT_WEB_BROWSERSLIST.join(',')) {
-    return 2017;
-  }
-
-  return browserslistToESVersion(browserslist);
-};
-
 export const pluginTarget = (): RsbuildPlugin => ({
   name: 'rsbuild:target',
 
@@ -27,14 +14,25 @@ export const pluginTarget = (): RsbuildPlugin => ({
         }
 
         const { browserslist } = environment;
-        const esVersion = await getESVersion(browserslist);
+
+        // skip calculation if the browserslist is the default value
+        const isDefaultBrowserslist =
+          browserslist.join(',') === DEFAULT_WEB_BROWSERSLIST.join(',');
 
         if (target === 'web-worker') {
-          chain.target(['webworker', `es${esVersion}`]);
+          chain.target(
+            isDefaultBrowserslist
+              ? ['webworker', 'es2017']
+              : // TODO: Rspack should support `browserslist:` for webworker target
+                ['webworker', 'es5'],
+          );
           return;
         }
 
-        chain.target(['web', `es${esVersion}`]);
+        const esQuery = isDefaultBrowserslist
+          ? 'es2017'
+          : (`browserslist:${browserslist.join(',')}` as const);
+        chain.target(['web', esQuery]);
       },
     });
   },

packages/core/tests/target.test.ts

@@ -10,7 +10,7 @@ describe('plugin-target', () => {
     },
     {
       browserslist: ['Chrome 100'],
-      expected: ['web', 'es2018'],
+      expected: ['web', 'browserslist:Chrome 100'],
     },
     {
       browserslist: null,

packages/core/tsconfig.json

@@ -30,7 +30,6 @@
       "rspack-manifest-plugin": ["./compiled/rspack-manifest-plugin"],
       "rsbuild-dev-middleware": ["./compiled/rsbuild-dev-middleware"],
       "launch-editor-middleware": ["./compiled/launch-editor-middleware"],
-      "browserslist-to-es-version": ["./compiled/browserslist-to-es-version"],
       "connect-history-api-fallback": [
         "./compiled/connect-history-api-fallback"
       ]