add env option - closes #1531

src/babel/helpers/merge.js

@@ -0,0 +1,17 @@
+import merge from "lodash/object/merge";
+
+export default function (dest, src) {
+  if (!dest || !src) return;
+
+  return merge(dest, src, function(a, b) {
+    if (Array.isArray(a)) {
+      var c = a.slice(0);
+      for (var v of b) {
+        if (a.indexOf(v) < 0) {
+          c.push(v);
+        }
+      }
+      return c;
+    }
+  });
+}

src/babel/tools/resolve-rc.js

@@ -1,5 +1,5 @@
 import stripJsonComments from "strip-json-comments";
-import merge from "lodash/object/merge";
+import merge from "../helpers/merge";
 import path from "path";
 import fs from "fs";
 
@@ -42,17 +42,7 @@ export default function (loc, opts = {}) {
       opts.babelrc.push(file);
 
       if (json.breakConfig) return;
-      merge(opts, json, function(a, b) {
-        if (Array.isArray(a)) {
-          var c = a.slice(0);
-          for (var v of b) {
-            if (a.indexOf(v) < 0) {
-              c.push(v);
-            }
-          }
-          return c;
-        }
-      });
+      merge(opts, json);
     }
 
     var up = path.dirname(start);

src/babel/transformation/file/index.js

@@ -19,6 +19,7 @@ import assign from "lodash/object/assign";
 import Logger from "./logger";
 import parse from "../../helpers/parse";
 import Scope from "../../traversal/scope";
+import merge from "../../helpers/merge";
 import slash from "slash";
 import clone from "lodash/lang/clone";
 import * as util from  "../../util";
@@ -106,6 +107,9 @@ export default class File {
       if (!option) this.log.error(`Unknown option: ${key}`, ReferenceError);
     }
 
+    var envKey = process.env.BABEL_ENV || process.env.NODE_ENV || "development";
+    if (opts.env) merge(opts, opts.env[envKey]);
+
     for (let key in File.options) {
       let option = File.options[key];
 

src/babel/transformation/file/options.json

@@ -20,6 +20,11 @@
     "default": {}
   },
 
+  "env": {
+    "hidden": true,
+    "default": {}
+  },
+
   "moduleId": {
     "description": "specify a custom name for module ids",
     "type": "string"