Add option --stats-out to emit webpack statistics output

readme.md

@@ -33,7 +33,7 @@ npm i -g @zeit/ncc
 ```bash
 $ ncc <cmd> <opts>
 ```
-Eg: 
+Eg:
 ```bash
 $ ncc build input.js -o dist
 ```
@@ -64,6 +64,7 @@ Outputs the Node.js compact build of `input.js` into `dist/index.js`.
   -q, --quiet              Disable build summaries / non-error outputs
   -w, --watch              Start a watched build
   --v8-cache               Emit a build using the v8 compile cache
+  --stats-out [file]       Emit webpack stats as json to the specified output file
 ```
 
 ### Execution Testing

src/cli.js

@@ -29,6 +29,7 @@ Options:
   -w, --watch              Start a watched build
   -t, --transpile-only     Use transpileOnly option with the ts-loader
   --v8-cache               Emit a build using the v8 compile cache
+  --stats-out [file]       Emit webpack stats as json to the specified output file
 `;
 
 // support an API mode for CLI testing
@@ -139,6 +140,7 @@ async function runCmd (argv, stdout, stderr) {
       "--v8-cache": Boolean,
       "--transpile-only": Boolean,
       "-t": "--transpile-only",
+      "--stats-out": String,
     }, {
       permissive: false,
       argv
@@ -154,6 +156,7 @@ async function runCmd (argv, stdout, stderr) {
   let run = false;
   let outDir = args["--out"];
   const quiet = args["--quiet"];
+  const statsOutFile = args["--stats-out"];
 
   switch (args._[0]) {
     case "cache":
@@ -232,7 +235,7 @@ async function runCmd (argv, stdout, stderr) {
         }
       );
 
-      async function handler ({ err, code, map, assets, symlinks }) {
+      async function handler ({ err, code, map, assets, symlinks, stats }) {
         // handle watch errors
         if (err) {
           stderr.write(err + '\n');
@@ -265,7 +268,7 @@ async function runCmd (argv, stdout, stderr) {
         }
 
         if (!quiet) {
-          stdout.write( 
+          stdout.write(
             renderSummary(
               code,
               map,
@@ -280,6 +283,9 @@ async function runCmd (argv, stdout, stderr) {
             stdout.write('Watching for changes...\n');
         }
 
+        if (statsOutFile)
+          writeFileSync(statsOutFile, JSON.stringify(stats.toJson()));
+
         if (run) {
           // find node_modules
           const root = resolve('/node_modules');

src/index.js

@@ -230,7 +230,7 @@ module.exports = (
                     "var e = new Error",
                     `if (typeof req === 'number' && __webpack_require__.m[req])\n` +
                     `  return __webpack_require__(req);\n` +
-                    `try { return require(req) }\n` + 
+                    `try { return require(req) }\n` +
                     `catch (e) { if (e.code !== 'MODULE_NOT_FOUND') throw e }\n` +
                     `var e = new Error`
                   );
@@ -279,7 +279,7 @@ module.exports = (
             const errLog = stats.compilation.errors.map(err => err.message).join('\n');
             return reject(new Error(errLog));
           }
-          resolve();
+          resolve(stats);
         });
       });
     })
@@ -298,7 +298,7 @@ module.exports = (
         return watchHandler({ err });
       if (stats.hasErrors())
         return watchHandler({ err: stats.toString() });
-      const returnValue = finalizeHandler();
+      const returnValue = finalizeHandler(stats);
       if (watchHandler)
         watchHandler(returnValue);
       else
@@ -331,7 +331,7 @@ module.exports = (
     };
   }
 
-  function finalizeHandler () {
+  function finalizeHandler (stats) {
     const assets = Object.create(null);
     getFlatFiles(mfs.data, assets, relocateLoader.getAssetPermissions);
     // filter symlinks to existing assets
@@ -414,7 +414,7 @@ module.exports = (
         map.mappings = ";" + map.mappings;
     }
 
-    return { code, map: map ? JSON.stringify(map) : undefined, assets, symlinks };
+    return { code, map: map ? JSON.stringify(map) : undefined, assets, symlinks, stats };
   }
 };
 

test/cli.js

@@ -63,5 +63,17 @@
     expect (code, stdout, stderr) {
       return stdout.toString().indexOf('tmp/index.js') !== -1;
     }
+  },
+  {
+    args: ["build", "-o", "tmp", "test/fixtures/test.mjs", "--stats-out", "tmp/stats.json"],
+    expect (code, stdout, stderr) {
+      const fs = require('fs');
+      try {
+        JSON.parse(fs.readFileSync('tmp/stats.json', 'utf8'));
+      } catch {
+        return false;
+      }
+      return true;
+    }
   }
-]
+]