Merge pull request #1538 from hypothesis/better-js-minification

Improve compression of JavaScript bundles

package.json

@@ -105,9 +105,9 @@
     "showdown": "^1.6.4",
     "sinon": "^7.2.3",
     "stringify": "^5.1.0",
+    "terser": "^4.4.0",
     "through2": "^3.0.0",
     "tiny-emitter": "^2.0.2",
-    "uglifyify": "^5.0.1",
     "unorm": "^1.3.3",
     "vinyl": "^2.2.0",
     "watchify": "^3.7.0",

scripts/gulp/create-bundle.js

@@ -14,9 +14,10 @@ const envify = require('loose-envify/custom');
 const gulpUtil = require('gulp-util');
 const mkdirp = require('mkdirp');
 const through = require('through2');
-const uglifyify = require('uglifyify');
 const watchify = require('watchify');
 
+const minifyStream = require('./minify-stream');
+
 const log = gulpUtil.log;
 
 function streamFinished(stream) {
@@ -223,10 +224,6 @@ module.exports = function createBundle(config, buildOpts) {
     }
   });
 
-  if (config.minify) {
-    bundle.transform({ global: true }, uglifyify);
-  }
-
   // Include or disable debugging checks in our code and dependencies by
   // replacing references to `process.env.NODE_ENV`.
   bundle.transform(
@@ -240,16 +237,23 @@ module.exports = function createBundle(config, buildOpts) {
     }
   );
 
+  if (config.minify) {
+    bundle.transform({ global: true }, minifyStream);
+  }
+
   function build() {
     const output = fs.createWriteStream(bundlePath);
     const b = bundle.bundle();
     b.on('error', function(err) {
       log('Build error', err.toString());
     });
-    const stream = b
-      .pipe(useExternalRequireName(externalRequireName))
-      .pipe(exorcist(sourcemapPath))
-      .pipe(output);
+    let stream = b.pipe(useExternalRequireName(externalRequireName));
+
+    if (config.minify) {
+      stream = stream.pipe(minifyStream());
+    }
+
+    stream.pipe(exorcist(sourcemapPath)).pipe(output);
     return streamFinished(stream);
   }
 

scripts/gulp/minify-stream.js

+'use strict';
+
+const { Transform } = require('stream');
+
+const terser = require('terser');
+
+/**
+ * Return a Node `Transform` stream that minifies JavaScript input.
+ *
+ * This is designed to be used both to process individual modules as a Browserify
+ * transform, and also to be applied to the output of the whole bundle to
+ * compress the module infrastructure that Browserify adds.
+ *
+ * @example
+ *   browserify(['src/app.js'])
+ *     .transform({ global: true }, minifyStream) // Minify individual modules
+ *     .pipe(minifyStream()) // Minify the code added by Browserify
+ *     .pipe(output);
+ */
+function minifyStream() {
+  return new Transform({
+    transform(data, encoding, callback) {
+      if (!this.chunks) {
+        this.chunks = [];
+      }
+      this.chunks.push(data);
+      callback();
+    },
+
+    flush(callback) {
+      const code = Buffer.concat(this.chunks).toString();
+      const minified = terser.minify(code, {
+        // See https://github.com/terser/terser#minify-options-structure
+        sourceMap: { url: 'inline' },
+      }).code;
+      this.push(minified);
+      callback();
+    },
+  });
+}
+
+module.exports = minifyStream;

yarn.lock

@@ -2205,6 +2205,11 @@ commander@^2.19.0, commander@~2.20.0:
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.20.0.tgz#d58bb2b5c1ee8f87b0d340027e9e94e222c5a422"
   integrity sha512-7j2y+40w61zy6YC2iRNpUe/NwhNyoXrYpHMrSunaMG64nRnaf96zO/KMQR4OyN/UnE5KLyEBnKHd4aG3rskjpQ==
 
+commander@^2.20.0:
+  version "2.20.3"
+  resolved "https://registry.yarnpkg.com/commander/-/commander-2.20.3.tgz#fd485e84c03eb4881c20722ba48035e8531aeb33"
+  integrity sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==
+
 commander@^4.0.1:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/commander/-/commander-4.0.1.tgz#b67622721785993182e807f4883633e6401ba53c"
@@ -7591,10 +7596,10 @@ source-map-resolve@^0.5.0, source-map-resolve@^0.5.2:
     source-map-url "^0.4.0"
     urix "^0.1.0"
 
-source-map-support@~0.5.10:
-  version "0.5.12"
-  resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.12.tgz#b4f3b10d51857a5af0138d3ce8003b201613d599"
-  integrity sha512-4h2Pbvyy15EE02G+JOZpUCmqWJuqrs+sEkzewTm++BPi7Hvn/HwcqLAcNxYAyI0x13CpPPn+kMjl+hplXMHITQ==
+source-map-support@~0.5.12:
+  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"
@@ -7981,14 +7986,14 @@ ternary@~1.0.0:
   resolved "https://registry.yarnpkg.com/ternary/-/ternary-1.0.0.tgz#45702725608c9499d46a9610e9b0e49ff26f789e"
   integrity sha1-RXAnJWCMlJnUapYQ6bDkn/JveJ4=
 
-terser@^3.7.5:
-  version "3.17.0"
-  resolved "https://registry.yarnpkg.com/terser/-/terser-3.17.0.tgz#f88ffbeda0deb5637f9d24b0da66f4e15ab10cb2"
-  integrity sha512-/FQzzPJmCpjAH9Xvk2paiWrFq+5M6aVOf+2KRbwhByISDX/EujxsK+BAvrhb6H+2rtrLCHK9N01wO014vrIwVQ==
+terser@^4.4.0:
+  version "4.4.0"
+  resolved "https://registry.yarnpkg.com/terser/-/terser-4.4.0.tgz#22c46b4817cf4c9565434bfe6ad47336af259ac3"
+  integrity sha512-oDG16n2WKm27JO8h4y/w3iqBGAOSCtq7k8dRmrn4Wf9NouL0b2WpMHGChFGZq4nFAQy1FsNJrVQHfurXOSTmOA==
   dependencies:
-    commander "^2.19.0"
+    commander "^2.20.0"
     source-map "~0.6.1"
-    source-map-support "~0.5.10"
+    source-map-support "~0.5.12"
 
 test-exclude@^5.2.3:
   version "5.2.3"
@@ -8267,17 +8272,6 @@ uglify-js@^3.1.4:
     commander "~2.20.0"
     source-map "~0.6.1"
 
-uglifyify@^5.0.1:
-  version "5.0.2"
-  resolved "https://registry.yarnpkg.com/uglifyify/-/uglifyify-5.0.2.tgz#7d0269885e09faa963208a9ec6721afcaf45fc50"
-  integrity sha512-NcSk6pgoC+IgwZZ2tVLVHq+VNKSvLPlLkF5oUiHPVOJI0s/OlSVYEGXG9PCAH0hcyFZLyvt4KBdPAQBRlVDn1Q==
-  dependencies:
-    convert-source-map "~1.1.0"
-    minimatch "^3.0.2"
-    terser "^3.7.5"
-    through "~2.3.4"
-    xtend "^4.0.1"
-
 ultron@~1.1.0:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/ultron/-/ultron-1.1.1.tgz#9fe1536a10a664a65266a1e3ccf85fd36302bc9c"