[preset-env] Add browserslistEnv option

packages/babel-helper-compilation-targets/src/index.js

@@ -205,6 +205,7 @@ export default function getTargets(
     const browsers = browserslist(browsersquery, {
       path: options.configPath,
       mobileToDesktop: true,
+      env: options.browserslistEnv,
     });
 
     const queryBrowsers = getLowestVersions(browsers);

packages/babel-helper-compilation-targets/test/custom-browserslist-env/.browserslistrc

@@ -0,0 +1,2 @@
+[custom]
+ie 11

packages/babel-helper-compilation-targets/test/custom-browserslist-env/custom-browserslist-env.spec.js

@@ -0,0 +1,10 @@
+import getTargets from "../..";
+
+it("allows custom browserslist env", () => {
+  const actual = getTargets(
+    {},
+    { configPath: __dirname, browserslistEnv: "custom" },
+  );
+
+  expect(actual).toEqual({ ie: "11.0.0" });
+});

packages/babel-preset-env/src/index.js

@@ -228,6 +228,7 @@ export default declare((api, opts) => {
     targets: optionsTargets,
     useBuiltIns,
     corejs: { version: corejs, proposals },
+    browserslistEnv,
   } = normalizeOptions(opts);
   // TODO: remove this in next major
   let hasUglifyTarget = false;
@@ -257,7 +258,7 @@ export default declare((api, opts) => {
   const targets = getTargets(
     // $FlowIgnore optionsTargets doesn't have an "uglify" property anymore
     (optionsTargets: InputTargets),
-    { ignoreBrowserslistConfig, configPath },
+    { ignoreBrowserslistConfig, configPath, browserslistEnv },
   );
   const include = transformIncludesAndExcludes(optionsInclude);
   const exclude = transformIncludesAndExcludes(optionsExclude);

packages/babel-preset-env/src/normalize-options.js

@@ -152,6 +152,20 @@ export const validateBoolOption = (
   return value;
 };
 
+export const validateStringOption = (
+  name: string,
+  value?: string,
+  defaultValue?: string,
+) => {
+  if (typeof value === "undefined") {
+    value = defaultValue;
+  } else if (typeof value !== "string") {
+    throw new Error(`Preset env: '${name}' option must be a string.`);
+  }
+
+  return value;
+};
+
 export const validateIgnoreBrowserslistConfig = (
   ignoreBrowserslistConfig: boolean,
 ) =>
@@ -295,5 +309,9 @@ export default function normalizeOptions(opts: Options) {
     spec: validateBoolOption(TopLevelOptions.spec, opts.spec, false),
     targets: normalizeTargets(opts.targets),
     useBuiltIns: useBuiltIns,
+    browserslistEnv: validateStringOption(
+      TopLevelOptions.browserslistEnv,
+      opts.browserslistEnv,
+    ),
   };
 }

packages/babel-preset-env/src/options.js

@@ -15,6 +15,7 @@ export const TopLevelOptions = {
   spec: "spec",
   targets: "targets",
   useBuiltIns: "useBuiltIns",
+  browserslistEnv: "browserslistEnv",
 };
 
 export const ModulesOption = {

packages/babel-preset-env/src/types.js

@@ -34,6 +34,7 @@ export type Options = {
   spec: boolean,
   targets: { ...InputTargets, uglify?: boolean },
   useBuiltIns: BuiltInsOption,
+  browserslistEnv: string,
 };
 
 // Babel

packages/babel-preset-env/test/fixtures/debug/browserslist-env/.browserslistrc

@@ -0,0 +1,2 @@
+[custom]
+ie 11

packages/babel-preset-env/test/fixtures/debug/browserslist-env/input.mjs

@@ -0,0 +1 @@
+import "core-js";

packages/babel-preset-env/test/fixtures/debug/browserslist-env/options.js

@@ -0,0 +1,14 @@
+module.exports = {
+  validateLogs: true,
+  ignoreOutput: true,
+  presets: [
+    [
+      "env",
+      {
+        debug: true,
+        browserslistEnv: "custom",
+        configPath: __dirname,
+      },
+    ],
+  ],
+};

packages/babel-preset-env/test/fixtures/debug/browserslist-env/stdout.txt

@@ -0,0 +1,44 @@
+@babel/preset-env: `DEBUG` option
+
+Using targets:
+{
+  "ie": "11"
+}
+
+Using modules transform: auto
+
+Using plugins:
+  proposal-nullish-coalescing-operator { "ie":"11" }
+  proposal-optional-chaining { "ie":"11" }
+  proposal-json-strings { "ie":"11" }
+  proposal-optional-catch-binding { "ie":"11" }
+  transform-parameters { "ie":"11" }
+  proposal-async-generator-functions { "ie":"11" }
+  proposal-object-rest-spread { "ie":"11" }
+  transform-dotall-regex { "ie":"11" }
+  proposal-unicode-property-regex { "ie":"11" }
+  transform-named-capturing-groups-regex { "ie":"11" }
+  transform-async-to-generator { "ie":"11" }
+  transform-exponentiation-operator { "ie":"11" }
+  transform-template-literals { "ie":"11" }
+  transform-literals { "ie":"11" }
+  transform-function-name { "ie":"11" }
+  transform-arrow-functions { "ie":"11" }
+  transform-classes { "ie":"11" }
+  transform-object-super { "ie":"11" }
+  transform-shorthand-properties { "ie":"11" }
+  transform-duplicate-keys { "ie":"11" }
+  transform-computed-properties { "ie":"11" }
+  transform-for-of { "ie":"11" }
+  transform-sticky-regex { "ie":"11" }
+  transform-unicode-regex { "ie":"11" }
+  transform-spread { "ie":"11" }
+  transform-destructuring { "ie":"11" }
+  transform-block-scoping { "ie":"11" }
+  transform-typeof-symbol { "ie":"11" }
+  transform-new-target { "ie":"11" }
+  transform-regenerator { "ie":"11" }
+  transform-modules-commonjs { "ie":"11" }
+  proposal-dynamic-import { "ie":"11" }
+
+Using polyfills: No polyfills were added, since the `useBuiltIns` option was not set.

packages/babel-preset-env/test/normalize-options.spec.js

@@ -5,6 +5,7 @@ const normalizeOptions = require("../lib/normalize-options.js");
 const {
   checkDuplicateIncludeExcludes,
   validateBoolOption,
+  validateStringOption,
   validateModulesOption,
   validateUseBuiltInsOption,
   normalizePluginName,
@@ -191,6 +192,28 @@ describe("normalize-options", () => {
     });
   });
 
+  describe("validateStringOption", () => {
+    it("`undefined` option default", () => {
+      expect(validateStringOption("test", undefined, "default")).toBe(
+        "default",
+      );
+    });
+
+    it("`value` option returns value", () => {
+      expect(validateStringOption("test", "value", "default")).toBe("value");
+    });
+
+    it("no default returns undefined", () => {
+      expect(validateStringOption("test", undefined)).toBe(undefined);
+    });
+
+    it("array option is invalid", () => {
+      expect(() => {
+        validateStringOption("test", [], "default");
+      }).toThrow();
+    });
+  });
+
   describe("checkDuplicateIncludeExcludes", function() {
     it("should throw if duplicate names in both", function() {
       expect(() => {