Avoid resolveTargets call if browsers is an empty array (#14294)

Co-authored-by: gaosheng08 <gaosheng08@meituan.com>
babel · Mar 14, 2022 · 8dcf3ef · 8dcf3ef
1 parent 4820ea0
commit 8dcf3ef
Show file tree

Hide file tree

Showing 2 changed files with 29 additions and 1 deletion.
diff --git a/packages/babel-helper-compilation-targets/src/index.ts b/packages/babel-helper-compilation-targets/src/index.ts
@@ -219,7 +219,10 @@ export default function getTargets(
     esmodules = false;
   }
 
-  if (browsers) {
+  // If current value of `browsers` is undefined (`ignoreBrowserslistConfig` should be `false`)
+  // or an empty array (without any user config, use default config),
+  // we don't need to call `resolveTargets` to execute the related methods of `browserslist` library.
+  if (browsers?.length) {
     const queryBrowsers = resolveTargets(browsers, options.browserslistEnv);
 
     if (esmodules === "intersect") {

diff --git a/packages/babel-helper-compilation-targets/test/targets-parser.spec.js b/packages/babel-helper-compilation-targets/test/targets-parser.spec.js
@@ -293,6 +293,31 @@ describe("getTargets", () => {
       },
     );
 
+    (process.env.BABEL_8_BREAKING ? it.skip : it)(
+      "'browsers' option will have no effect if it is an empty array - Babel 7",
+      () => {
+        expect(getTargets({ esmodules: "intersect", browsers: [] })).toEqual(
+          getTargets({ esmodules: "intersect" }),
+        );
+      },
+    );
+
+    it("The final 'browsers' handled variable will have no effect if it is an empty array", () => {
+      expect(getTargets({ esmodules: "intersect", browsers: [] })).toEqual(
+        getTargets(
+          { esmodules: "intersect" },
+          { ignoreBrowserslistConfig: true },
+        ),
+      );
+    });
+
+    it("'resolveTargets' will be called rightly if 'browsers' is an array with some value", () => {
+      // 'test' is an unknown browser query, so methods of 'browserslist' library will throw an error
+      expect(() =>
+        getTargets({ esmodules: "intersect", browsers: ["test"] }),
+      ).toThrow();
+    });
+
     (process.env.BABEL_8_BREAKING ? it : it.skip)(
       "'intersect' behaves like no-op if no browsers are specified",
       () => {