Update terser to v5 in metro-minify-terser (facebook#606)

Summary:
**Summary**

Update terser to the latest version that supports more modern js syntax like optional chaining. The main breaking change in v5 is that minify is now async. To support this I also needed to add async minifier support in metro-transform-worker.

**Test plan**

- Run tests
- Test building my app bundle with minifier terser and untransformed optional chaining

Pull Request resolved: facebook#606

Reviewed By: feedthejim

Differential Revision: D24883529

Pulled By: rh389

fbshipit-source-id: c9ed893535337ecc1ce16e433e3d689c2037be0a

packages/metro-minify-terser/package.json

@@ -13,6 +13,6 @@
   },
   "license": "MIT",
   "dependencies": {
-    "terser": "^4.6.3"
+    "terser": "^5.10.0"
   }
 }

packages/metro-minify-terser/src/__tests__/minify-test.js

@@ -17,10 +17,10 @@ const minify = require('..');
 
 jest.mock('terser', () => ({
   minify: jest.fn(code => {
-    return {
+    return Promise.resolve({
       code: code.replace(/(^|\W)\s+/g, '$1'),
       map: {},
-    };
+    });
   }),
 }));
 const {objectContaining} = expect;
@@ -57,12 +57,12 @@ describe('Minification:', () => {
     /* $FlowFixMe(>=0.99.0 site=react_native_fb) This comment suppresses an
      * error found when Flow v0.99 was deployed. To see the error, delete this
      * comment and run Flow. */
-    terser.minify.mockReturnValue({code: '', map: '{}'});
+    terser.minify.mockResolvedValue({code: '', map: '{}'});
     map = getFakeMap();
   });
 
-  it('passes file name, code, and source map to `terser`', () => {
-    minify({
+  it('passes file name, code, and source map to `terser`', async () => {
+    await minify({
       ...baseOptions,
       code,
       map,
@@ -80,21 +80,21 @@ describe('Minification:', () => {
     );
   });
 
-  it('returns the code provided by terser', () => {
+  it('returns the code provided by terser', async () => {
     /* $FlowFixMe(>=0.99.0 site=react_native_fb) This comment suppresses an
      * error found when Flow v0.99 was deployed. To see the error, delete this
      * comment and run Flow. */
-    terser.minify.mockReturnValue({code, map: '{}'});
-    const result = minify(baseOptions);
+    terser.minify.mockResolvedValue({code, map: '{}'});
+    const result = await minify(baseOptions);
     expect(result.code).toBe(code);
   });
 
-  it('parses the source map object provided by terser and sets the sources property', () => {
+  it('parses the source map object provided by terser and sets the sources property', async () => {
     /* $FlowFixMe(>=0.99.0 site=react_native_fb) This comment suppresses an
      * error found when Flow v0.99 was deployed. To see the error, delete this
      * comment and run Flow. */
-    terser.minify.mockReturnValue({map: JSON.stringify(map), code: ''});
-    const result = minify({...baseOptions, filename});
+    terser.minify.mockResolvedValue({map: JSON.stringify(map), code: ''});
+    const result = await minify({...baseOptions, filename});
     expect(result.map).toEqual({...map, sources: [filename]});
   });
 });

packages/metro-minify-terser/src/minifier.js

@@ -15,8 +15,8 @@ import type {MinifierOptions, MinifierResult} from 'metro-transform-worker';
 
 const terser = require('terser');
 
-function minifier(options: MinifierOptions): MinifierResult {
-  const result = minify(options);
+async function minifier(options: MinifierOptions): Promise<MinifierResult> {
+  const result = await minify(options);
 
   if (!options.map || result.map == null) {
     return {code: result.code};
@@ -27,10 +27,12 @@ function minifier(options: MinifierOptions): MinifierResult {
   return {code: result.code, map: {...map, sources: [options.filename]}};
 }
 
-function minify({code, map, reserved, config}: MinifierOptions): {
-  code: string,
-  map: ?string,
-} {
+async function minify({
+  code,
+  map,
+  reserved,
+  config,
+}: MinifierOptions): Promise<{code: string, map: ?string}> {
   const options = {
     ...config,
     mangle:
@@ -53,11 +55,7 @@ function minify({code, map, reserved, config}: MinifierOptions): {
   /* $FlowFixMe(>=0.111.0 site=react_native_fb) This comment suppresses an
    * error found when Flow v0.111 was deployed. To see the error, delete this
    * comment and run Flow. */
-  const result = terser.minify(code, options);
-
-  if (result.error) {
-    throw result.error;
-  }
+  const result = await terser.minify(code, options);
 
   return {
     code: result.code,

yarn.lock

@@ -6909,14 +6909,22 @@ source-map-resolve@^0.5.0:
     source-map-url "^0.4.0"
     urix "^0.1.0"
 
-source-map-support@^0.5.16, source-map-support@^0.5.6, source-map-support@~0.5.12:
+source-map-support@^0.5.16, source-map-support@^0.5.6:
   version "0.5.16"
   resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.16.tgz#0ae069e7fe3ba7538c64c98515e35339eac5a042"
   integrity sha512-efyLRJDr68D9hBBNIPWFjhpFzURh+KJykQwvMyW5UiZzYwoF6l4YMMDIJJEyFWxWCqfyxLzz6tSfUFR+kXXsVQ==
   dependencies:
     buffer-from "^1.0.0"
     source-map "^0.6.0"
 
+source-map-support@~0.5.20:
+  version "0.5.21"
+  resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.21.tgz#04fe7c7f9e1ed2d662233c28cb2b35b9f63f6e4f"
+  integrity sha512-uBHU3L3czsIyYXKX88fdrGovxdSCoTGDRZ6SYXtSRxLZUzHg5P/66Ht6uoUlHu9EZod+inXhKo3qQgwXUT/y1w==
+  dependencies:
+    buffer-from "^1.0.0"
+    source-map "^0.6.0"
+
 source-map-url@^0.4.0:
   version "0.4.0"
   resolved "https://registry.yarnpkg.com/source-map-url/-/source-map-url-0.4.0.tgz#3e935d7ddd73631b97659956d55128e87b5084a3"
@@ -6932,7 +6940,7 @@ source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.1:
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
   integrity sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==
 
-source-map@^0.7.3:
+source-map@^0.7.3, source-map@~0.7.2:
   version "0.7.3"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.7.3.tgz#5302f8169031735226544092e64981f751750383"
   integrity sha512-CkCj6giN3S+n9qrYiBTX5gystlENnRW5jZeNLHpe6aue+SrHcG5VYwujhW9s4dY31mEGsxBDrHR6oI69fTXsaQ==
@@ -7346,14 +7354,14 @@ terminal-link@^2.0.0:
     ansi-escapes "^4.2.1"
     supports-hyperlinks "^2.0.0"
 
-terser@^4.6.3:
-  version "4.6.7"
-  resolved "https://registry.yarnpkg.com/terser/-/terser-4.6.7.tgz#478d7f9394ec1907f0e488c5f6a6a9a2bad55e72"
-  integrity sha512-fmr7M1f7DBly5cX2+rFDvmGBAaaZyPrHYK4mMdHEDAdNTqXSZgSOfqsfGq2HqPGT/1V0foZZuCZFx8CHKgAk3g==
+terser@^5.10.0:
+  version "5.10.0"
+  resolved "https://registry.yarnpkg.com/terser/-/terser-5.10.0.tgz#b86390809c0389105eb0a0b62397563096ddafcc"
+  integrity sha512-AMmF99DMfEDiRJfxfY5jj5wNH/bYO09cniSqhfoyxc8sFoYIgkJy86G04UoZU5VjlpnplVu0K6Tx6E9b5+DlHA==
   dependencies:
     commander "^2.20.0"
-    source-map "~0.6.1"
-    source-map-support "~0.5.12"
+    source-map "~0.7.2"
+    source-map-support "~0.5.20"
 
 test-exclude@^6.0.0:
   version "6.0.0"