Minify JSON (#471)

* uglify-json

* throw on error

* Clean up JSONAsset

Don’t extend from JSAsset

src/assets/JSONAsset.js

@@ -1,14 +1,28 @@
-const JSAsset = require('./JSAsset');
+const Asset = require('../Asset');
+const {minify} = require('uglify-es');
 
-class JSONAsset extends JSAsset {
-  async load() {
-    return 'module.exports = ' + (await super.load()) + ';';
+class JSONAsset extends Asset {
+  constructor(name, pkg, options) {
+    super(name, pkg, options);
+    this.type = 'js';
   }
 
-  parse() {}
-  collectDependencies() {}
-  pretransform() {}
-  transform() {}
+  generate() {
+    let code = `module.exports = ${this.contents};`;
+
+    if (this.options.minify) {
+      let minified = minify(code);
+      if (minified.error) {
+        throw minified.error;
+      }
+
+      code = minified.code;
+    }
+
+    return {
+      js: code
+    };
+  }
 }
 
 module.exports = JSONAsset;

test/integration/uglify-json/index.json

@@ -0,0 +1,3 @@
+{
+    "test": "test"
+}

test/javascript.js

@@ -383,4 +383,13 @@ describe('javascript', function() {
     assert.equal(typeof output.test, 'function');
     assert.equal(output.test(), 'pkg-main-module');
   });
+
+  it('should minify JSON files', async function() {
+    await bundle(__dirname + '/integration/uglify-json/index.json', {
+      production: true
+    });
+
+    let json = fs.readFileSync(__dirname + '/dist/index.js', 'utf8');
+    assert(json.includes('test:"test"'));
+  });
 });