add npm-link support

Author: tuchk4

packages/react-scripts/config/paths.js

@@ -13,6 +13,10 @@ var path = require('path');
 var fs = require('fs');
 var url = require('url');
 
+// @remove-on-eject-begin
+var isReactScriptsLinked = require('../utils/isReactScriptsLinked');
+// @remove-on-eject-end
+
 // Make sure any symlinks in the project folder are resolved:
 // https://github.com/facebookincubator/create-react-app/issues/637
 var appDirectory = fs.realpathSync(process.cwd());
@@ -113,7 +117,7 @@ module.exports = {
 };
 
 // config before publish: we're in ./packages/react-scripts/config/
-if (__dirname.indexOf(path.join('packages', 'react-scripts', 'config')) !== -1) {
+if (!isReactScriptsLinked() && __dirname.indexOf(path.join('packages', 'react-scripts', 'config')) !== -1) {
   module.exports = {
     appBuild: resolveOwn('../../../build'),
     appPublic: resolveOwn('../template/public'),

packages/react-scripts/scripts/eject.js

@@ -11,12 +11,15 @@ var createJestConfig = require('../utils/createJestConfig');
 var fs = require('fs-extra');
 var path = require('path');
 var paths = require('../config/paths');
+var isReactScriptsLinked = require('../utils/isReactScriptsLinked');
 var prompt = require('react-dev-utils/prompt');
 var spawnSync = require('cross-spawn').sync;
 var chalk = require('chalk');
 var green = chalk.green;
 var cyan = chalk.cyan;
 
+var reactScriptsLinked = isReactScriptsLinked();
+
 prompt(
   'Are you sure you want to eject? This action is permanent.',
   false
@@ -28,8 +31,15 @@ prompt(
 
   console.log('Ejecting...');
 
+  // NOTE: get ownPath and appPath from config/paths.js ?
   var ownPath = path.join(__dirname, '..');
-  var appPath = path.join(ownPath, '..', '..');
+  var appPath;
+
+  if (reactScriptsLinked) {
+    appPath = path.resolve('.');
+  } else {
+    appPath = path.join(ownPath, '..', '..');
+  }
 
   function verifyAbsent(file) {
     if (fs.existsSync(path.join(appPath, file))) {
@@ -135,7 +145,6 @@ prompt(
   );
 
   // Add Babel config
-
   console.log('  Adding ' + cyan('Babel') + ' preset');
   appPackage.babel = babelConfig;
 
@@ -151,11 +160,15 @@ prompt(
 
   if (fs.existsSync(paths.yarnLockFile)) {
     console.log(cyan('Running yarn...'));
-    fs.removeSync(ownPath);
+    if (!reactScriptsLinked) {
+      fs.removeSync(ownPath);
+    }
     spawnSync('yarnpkg', [], {stdio: 'inherit'});
   } else {
     console.log(cyan('Running npm install...'));
-    fs.removeSync(ownPath);
+    if (!reactScriptsLinked) {
+      fs.removeSync(ownPath);
+    }
     spawnSync('npm', ['install'], {stdio: 'inherit'});
   }
   console.log(green('Ejected successfully!'));

packages/react-scripts/utils/isReactScriptsLinked.js

@@ -0,0 +1,7 @@
+var path = require('path');
+var fs = require('fs');
+
+module.exports = () => {
+  var localReactScriptsPath = path.resolve('node_modules/react-scripts');
+  return fs.existsSync(localReactScriptsPath) && fs.lstatSync(localReactScriptsPath).isSymbolicLink();
+};