Use Object Spread Syntax (#7777)

* Use Object Spread Syntax

* Nits

packages/babel-cli/src/babel/util.js

@@ -51,9 +51,10 @@ export function log(msg, force) {
 }
 
 export function transform(filename, code, opts, callback) {
-  opts = Object.assign({}, opts, {
+  opts = {
+    ...opts,
     filename,
-  });
+  };
 
   babel.transform(code, opts, callback);
 }

packages/babel-code-frame/src/index.js

@@ -38,12 +38,15 @@ function getMarkerLines(
   source: Array<string>,
   opts: Object,
 ): { start: number, end: number, markerLines: Object } {
-  const startLoc: Location = Object.assign(
-    {},
-    { column: 0, line: -1 },
-    loc.start,
-  );
-  const endLoc: Location = Object.assign({}, startLoc, loc.end);
+  const startLoc: Location = {
+    column: 0,
+    line: -1,
+    ...loc.start,
+  };
+  const endLoc: Location = {
+    ...startLoc,
+    ...loc.end,
+  };
   const { linesAbove = 2, linesBelow = 3 } = opts || {};
   const startLine = startLoc.line;
   const startColumn = startLoc.column;

packages/babel-core/src/config/config-chain.js

@@ -480,7 +480,9 @@ function emptyChain(): ConfigChain {
 }
 
 function normalizeOptions(opts: ValidatedOptions): ValidatedOptions {
-  const options = Object.assign({}, opts);
+  const options = {
+    ...opts,
+  };
   delete options.extends;
   delete options.env;
   delete options.plugins;

packages/babel-core/src/config/full.js

@@ -174,7 +174,10 @@ const loadDescriptor = makeWeakCache(
 
     let item = value;
     if (typeof value === "function") {
-      const api = Object.assign({}, context, makeAPI(cache));
+      const api = {
+        ...context,
+        ...makeAPI(cache),
+      };
       try {
         item = value(api, options, dirname);
       } catch (e) {
@@ -229,9 +232,13 @@ const instantiatePlugin = makeWeakCache(
   ): Plugin => {
     const pluginObj = validatePluginObject(value);
 
-    const plugin = Object.assign({}, pluginObj);
+    const plugin = {
+      ...pluginObj,
+    };
     if (plugin.visitor) {
-      plugin.visitor = traverse.explode(Object.assign({}, plugin.visitor));
+      plugin.visitor = traverse.explode({
+        ...plugin.visitor,
+      });
     }
 
     if (plugin.inherits) {

packages/babel-core/src/transform-file-sync.js

@@ -12,7 +12,10 @@ export default function transformFileSync(
   if (opts == null) {
     options = { filename };
   } else if (opts && typeof opts === "object") {
-    options = Object.assign({}, opts, { filename });
+    options = {
+      ...opts,
+      filename,
+    };
   }
 
   const config = loadConfig(options);

packages/babel-core/src/transform-file.js

@@ -19,7 +19,10 @@ export default ((function transformFile(filename, opts, callback) {
   if (opts == null) {
     options = { filename };
   } else if (opts && typeof opts === "object") {
-    options = Object.assign({}, opts, { filename });
+    options = {
+      ...opts,
+      filename,
+    };
   }
 
   process.nextTick(() => {

packages/babel-core/src/transformation/normalize-opts.js

@@ -22,36 +22,38 @@ export default function normalizeOptions(config: ResolvedConfig): {} {
 
   const opts = config.options;
 
-  const options = Object.assign({}, opts, {
-    parserOpts: Object.assign(
-      {
-        sourceType:
-          path.extname(filenameRelative) === ".mjs" ? "module" : sourceType,
-        sourceFileName: filename,
-        plugins: [],
-      },
-      opts.parserOpts,
-    ),
-    generatorOpts: Object.assign(
-      {
-        // General generator flags.
-        filename,
-        auxiliaryCommentBefore: opts.auxiliaryCommentBefore,
-        auxiliaryCommentAfter: opts.auxiliaryCommentAfter,
-        retainLines: opts.retainLines,
-        comments,
-        shouldPrintComment: opts.shouldPrintComment,
-        compact,
-        minified: opts.minified,
+  const options = {
+    ...opts,
 
-        // Source-map generation flags.
-        sourceMaps,
-        sourceRoot,
-        sourceFileName,
-      },
-      opts.generatorOpts,
-    ),
-  });
+    parserOpts: {
+      sourceType:
+        path.extname(filenameRelative) === ".mjs" ? "module" : sourceType,
+
+      sourceFileName: filename,
+      plugins: [],
+      ...opts.parserOpts,
+    },
+
+    generatorOpts: {
+      // General generator flags.
+      filename,
+
+      auxiliaryCommentBefore: opts.auxiliaryCommentBefore,
+      auxiliaryCommentAfter: opts.auxiliaryCommentAfter,
+      retainLines: opts.retainLines,
+      comments,
+      shouldPrintComment: opts.shouldPrintComment,
+      compact,
+      minified: opts.minified,
+
+      // Source-map generation flags.
+      sourceMaps,
+
+      sourceRoot,
+      sourceFileName,
+      ...opts.generatorOpts,
+    },
+  };
 
   for (const plugins of config.passes) {
     for (const plugin of plugins) {

packages/babel-helper-member-expression-to-functions/src/index.js

@@ -82,5 +82,8 @@ const handle = {
 // Optionally, a memoize method may be defined on the state, which will be
 // called when the member is a self-referential update.
 export default function memberExpressionToFunctions(path, visitor, state) {
-  path.traverse(visitor, Object.assign({}, state, handle));
+  path.traverse(visitor, {
+    ...state,
+    ...handle,
+  });
 }

packages/babel-helper-module-imports/src/import-injector.js

@@ -170,7 +170,9 @@ export default class ImportInjector {
       optsList.push(importedSource);
     }
 
-    const newOpts = Object.assign({}, this._defaultOpts);
+    const newOpts = {
+      ...this._defaultOpts,
+    };
     for (const opts of optsList) {
       if (!opts) continue;
       Object.keys(newOpts).forEach(key => {

packages/babel-helper-plugin-utils/src/index.js

@@ -34,7 +34,10 @@ function copyApiObject(api) {
     }
   }
 
-  return Object.assign({}, proto, api);
+  return {
+    ...proto,
+    ...api,
+  };
 }
 
 function has(obj, key) {

packages/babel-preset-env/src/index.js

@@ -95,7 +95,9 @@ export const isPluginRequired = (
 };
 
 const getBuiltInTargets = targets => {
-  const builtInTargets = Object.assign({}, targets);
+  const builtInTargets = {
+    ...targets,
+  };
   if (builtInTargets.uglify != null) {
     delete builtInTargets.uglify;
   }

packages/babel-preset-env/src/normalize-options.js

@@ -177,7 +177,9 @@ export default function normalizeOptions(opts: Options) {
       false,
     ),
     spec: validateBoolOption("loose", opts.spec, false),
-    targets: Object.assign({}, opts.targets),
+    targets: {
+      ...opts.targets,
+    },
     useBuiltIns: validateUseBuiltInsOption(opts.useBuiltIns),
   };
 }

packages/babel-register/src/node.js

@@ -39,11 +39,12 @@ function mtime(filename) {
 function compile(code, filename) {
   // merge in base options and resolve all the plugins and presets relative to this file
   const opts = new OptionManager().init(
-    Object.assign(
-      { sourceRoot: path.dirname(filename) }, // sourceRoot can be overwritten
-      deepClone(transformOpts),
-      { filename },
-    ),
+    // sourceRoot can be overwritten
+    {
+      sourceRoot: path.dirname(filename),
+      ...deepClone(transformOpts),
+      filename,
+    },
   );
 
   // Bail out ASAP if the file has been ignored.
@@ -109,7 +110,9 @@ register({
 
 export default function register(opts?: Object = {}) {
   // Clone to avoid mutating the arguments object with the 'delete's below.
-  opts = Object.assign({}, opts);
+  opts = {
+    ...opts,
+  };
   if (opts.extensions) hookExtensions(opts.extensions);
 
   if (opts.cache === false && cache) {
@@ -123,7 +126,9 @@ export default function register(opts?: Object = {}) {
   delete opts.extensions;
   delete opts.cache;
 
-  transformOpts = Object.assign({}, opts);
+  transformOpts = {
+    ...opts,
+  };
 
   let { cwd = "." } = transformOpts;
 

packages/babel-template/src/options.js

@@ -44,7 +44,10 @@ export function merge(a: TemplateOpts, b: TemplateOpts): TemplateOpts {
   } = b;
 
   return {
-    parser: Object.assign({}, a.parser, b.parser),
+    parser: {
+      ...a.parser,
+      ...b.parser,
+    },
     placeholderWhitelist,
     placeholderPattern,
     preserveComments,

packages/babel-template/src/parse.js

@@ -134,14 +134,12 @@ type MetadataState = {
 };
 
 function parseWithCodeFrame(code: string, parserOpts: {}): BabelNodeFile {
-  parserOpts = Object.assign(
-    {
-      allowReturnOutsideFunction: true,
-      allowSuperOutsideMethod: true,
-      sourceType: "module",
-    },
-    parserOpts,
-  );
+  parserOpts = {
+    allowReturnOutsideFunction: true,
+    allowSuperOutsideMethod: true,
+    sourceType: "module",
+    ...parserOpts,
+  };
 
   try {
     return parse(code, parserOpts);

packages/babel-types/src/clone/cloneNode.js

@@ -62,7 +62,9 @@ export default function cloneNode<T: Object>(node: T, deep: boolean = true): T {
     newNode.trailingComments = node.trailingComments;
   }
   if (has(node, "extra")) {
-    newNode.extra = Object.assign({}, node.extra);
+    newNode.extra = {
+      ...node.extra,
+    };
   }
 
   return newNode;

packages/babylon/src/index.js

@@ -19,7 +19,9 @@ plugins.typescript = typescriptPlugin;
 
 export function parse(input: string, options?: Options): File {
   if (options && options.sourceType === "unambiguous") {
-    options = Object.assign({}, options);
+    options = {
+      ...options,
+    };
     try {
       options.sourceType = "module";
       const parser = getParser(options, input);