Implement transform function using jscodeshift

- rename paths to babelRC
- create `writeBabelRCJS` for overwriting `.babelrc.js`

src/bin.js

@@ -1,6 +1,13 @@
 const path = require('path');
-const { isAcceptedNodeVersion, writePackageJSON, writeBabelRC, writeMochaOpts, installDeps } = require('.');
 const globby = require('globby');
+const {
+  isAcceptedNodeVersion,
+  writePackageJSON,
+  writeBabelRC,
+  writeMochaOpts,
+  installDeps,
+  writeBabelRCJS
+} = require('.');
 
 if (!isAcceptedNodeVersion()) {
   throw new Error("Babel 7 will only support Node 4 and higher");
@@ -14,7 +21,8 @@ async function hasFlow() {
 // TOOD: allow passing a specific path
 (async () => {
   // account for nested babelrc's
-  const paths = await globby(['**/.babelrc', '!**/node_modules/**']);
+  const babelRC = await globby(['**/.babelrc', '!**/node_modules/**']);
+  const babelRCJS = await globby(['**/.babelrc.js', '!**/node_modules/**']);
   const packages = await globby(['**/package.json', '!**/node_modules/**']);
   const mochaOpts = await globby(['**/mocha.opts', '!**/node_modules/**']);
   const flow = await hasFlow();
@@ -25,11 +33,12 @@ async function hasFlow() {
 
   // if not a monorepo
   if (packages.length === 1) {
-    if (paths.length > 1) {
+    if (babelRC.length > 1) {
       console.log("We suggest using the new 'overrides' option instead of nested .babelrc's, can check out http://new.babeljs.io/docs/en/next/babelrc.html#overrides");
       console.log("");
     }
-    paths.forEach(p => writeBabelRC(p, upgradeOptions));
+    babelRC.forEach(p => writeBabelRC(p, upgradeOptions));
+    babelRCJS.forEach(p => writeBabelRCJS(p));
   }
 
   mochaOpts.forEach(p => writeMochaOpts(p, upgradeOptions));

src/index.js

@@ -10,6 +10,7 @@ const writeFile = require('write');
 const crossSpawn = require('cross-spawn');
 const hasYarn = require('has-yarn');
 
+const transform = require('./transform');
 const upgradeDeps = require('./upgradeDeps');
 const upgradeConfig = require('./upgradeConfig');
 
@@ -118,6 +119,17 @@ async function writeBabelRC(configPath, options) {
   }
 }
 
+async function writeBabelRCJS(configPath) {
+  try {
+    const rawFile = (await pify(fs.readFile)(configPath)).toString('utf8');
+    const res = transform(rawFile);
+
+    await pify(fs.writeFile)(configPath, res); // overwrite
+  } catch (e) {
+    console.log(e)
+  }
+}
+
 async function writeMochaOpts(configPath) {
   let rawFile = (await pify(fs.readFile)(configPath)).toString('utf8');
   await writeFile(configPath, replaceMocha(rawFile));
@@ -132,4 +144,5 @@ module.exports = {
   getLatestVersion,
   writeMochaOpts,
   installDeps,
+  writeBabelRCJS
 };

src/transform.js

@@ -0,0 +1,31 @@
+const jscodeshift = require('jscodeshift');
+const packageData = require('./packageData');
+
+// for .babelrc.js
+function transform(src) {
+  const res = jscodeshift(src)
+    .find(jscodeshift.Property)
+    .forEach((node) => {
+      const type = node.value.key.name;
+      const value = node.value.value;
+
+      if (type === 'plugins') {
+        if (value.type === 'ArrayExpression') {
+          value.elements.forEach(el => {
+            el.value = packageData.plugins[el.value] || el.value;
+          })
+        }
+      } else if (type === 'presets') {
+        if (value.type === 'ArrayExpression') {
+          value.elements.forEach(el => {
+            el.value = packageData.presets[el.value] || el.value;
+          })
+        }
+      }
+    })
+    .toSource();
+
+  return res;
+}
+
+module.exports = transform;