Use JSONStream and createWriteStream() to output large json stats obj…

…ects

with Better tests

package.json

@@ -33,6 +33,7 @@
     "views"
   ],
   "dependencies": {
+    "JSONStream": "^1.3.1",
     "acorn": "^5.1.1",
     "chalk": "^1.1.3",
     "commander": "^2.9.0",

src/BundleAnalyzerPlugin.js

@@ -1,8 +1,7 @@
-const fs = require('fs');
 const path = require('path');
-const mkdir = require('mkdirp');
 const { bold } = require('chalk');
 
+const { streamObjectToJson } = require('./fileUtils');
 const Logger = require('./Logger');
 const viewer = require('./viewer');
 
@@ -61,15 +60,18 @@ class BundleAnalyzerPlugin {
     });
   }
 
-  generateStatsFile(stats) {
+  async generateStatsFile(stats) {
     const statsFilepath = path.resolve(this.compiler.outputPath, this.opts.statsFilename);
 
-    mkdir.sync(path.dirname(statsFilepath));
-
-    fs.writeFileSync(
-      statsFilepath,
-      JSON.stringify(stats, null, 2)
-    );
+    try {
+      await streamObjectToJson(statsFilepath, stats);
+    } catch (err) {
+      this.logger.error(
+        `${bold('Webpack Bundle Analyzer')} error saving stats file to ${bold(statsFilepath)}.`,
+        JSON.stringify(err, null, "\n") // eslint-disable-line quotes
+      );
+      return;
+    }
 
     this.logger.info(
       `${bold('Webpack Bundle Analyzer')} saved stats file to ${bold(statsFilepath)}`

src/fileUtils.js

@@ -0,0 +1,29 @@
+const fs = require('fs');
+const path = require('path');
+const mkdir = require('mkdirp');
+const JSONStream = require('JSONStream');
+
+module.exports = {
+  streamObjectToJson
+};
+
+async function streamObjectToJson(filepath, data) {
+  await new Promise((resolve, reject) => {
+    mkdir.sync(path.dirname(filepath));
+
+    const transformStream = JSONStream.stringifyObject();
+    const writableStream = fs.createWriteStream(filepath);
+    transformStream.pipe(writableStream);
+    transformStream.on('error', (err) => {
+      reject(err);
+    });
+    transformStream.on('end', () => {
+      writableStream.end();
+      resolve();
+    });
+    Object.keys(data).forEach((key) => {
+      transformStream.write([key, data[key]]);
+    });
+    transformStream.end();
+  });
+}

test/fileUtils.js

@@ -0,0 +1,45 @@
+const fs = require('fs');
+const del = require('del');
+const path = require('path');
+
+const { streamObjectToJson } = require('../lib/fileUtils');
+
+const OUTPUT_DIR = `${__dirname}/output`;
+
+describe('fileUtils', function () {
+  before(function () {
+    del.sync(`${__dirname}/output`);
+  });
+
+  afterEach(function () {
+    del.sync(`${__dirname}/output`);
+  });
+
+  it('should print objects to files', async function () {
+    const statsFilename = path.resolve(OUTPUT_DIR, 'stats.json');
+    await streamObjectToJson(statsFilename, {
+      string: 'webpack-bundle-analyzer',
+      list: ['foo', 'bar', 'baz'],
+      obj: {
+        name: 'webpack-bundle-analyzer',
+        foo: 'bar',
+        baz: null
+      }
+    });
+
+    await setImmediate(() => {
+      expect(fs.existsSync(statsFilename)).to.be.true;
+
+      const fileContent = fs.readFileSync(statsFilename, 'utf8');
+      expect(JSON.parse(fileContent)).to.deep.equal({
+        string: 'webpack-bundle-analyzer',
+        list: ['foo', 'bar', 'baz'],
+        obj: {
+          name: 'webpack-bundle-analyzer',
+          foo: 'bar',
+          baz: null
+        }
+      });
+    });
+  });
+});

yarn.lock

@@ -2,6 +2,13 @@
 # yarn lockfile v1
 
 
+JSONStream@^1.3.1:
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/JSONStream/-/JSONStream-1.3.1.tgz#707f761e01dae9e16f1bcf93703b78c70966579a"
+  dependencies:
+    jsonparse "^1.2.0"
+    through ">=2.2.7 <3"
+
 abbrev@1:
   version "1.1.0"
   resolved "https://registry.npmjs.org/abbrev/-/abbrev-1.1.0.tgz#d0554c2256636e2f56e7c2e5ad183f859428d81f"
@@ -2871,6 +2878,10 @@ jsonify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.npmjs.org/jsonify/-/jsonify-0.0.0.tgz#2c74b6ee41d93ca51b7b5aaee8f503631d252a73"
 
+jsonparse@^1.2.0:
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/jsonparse/-/jsonparse-1.3.1.tgz#3f4dae4a91fac315f71062f8521cc239f1366280"
+
 jsonpointer@^4.0.0:
   version "4.0.1"
   resolved "https://registry.npmjs.org/jsonpointer/-/jsonpointer-4.0.1.tgz#4fd92cb34e0e9db3c89c8622ecf51f9b978c6cb9"
@@ -4840,7 +4851,7 @@ through2@~0.2.3:
     readable-stream "~1.1.9"
     xtend "~2.1.1"
 
-through@^2.3.6:
+"through@>=2.2.7 <3", through@^2.3.6:
   version "2.3.8"
   resolved "https://registry.npmjs.org/through/-/through-2.3.8.tgz#0dd4c9ffaabc357960b1b724115d7e0e86a2e1f5"