[refactor] add babel

.babelrc

@@ -0,0 +1,7 @@
+{
+  "presets": [
+    [
+      "es2015"
+    ]
+  ]
+}

package.json

@@ -1,10 +1,12 @@
 {
   "name": "simple-jsonp-promise",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "build": "babel index.js --out-dir .",
+    "prepublish": "yarn run build"
   },
   "repository": {
     "type": "git",
@@ -19,5 +21,9 @@
   "bugs": {
     "url": "https://github.com/liziqiang/simple-jsonp-promise/issues"
   },
-  "homepage": "https://github.com/liziqiang/simple-jsonp-promise#readme"
+  "homepage": "https://github.com/liziqiang/simple-jsonp-promise#readme",
+  "dependencies": {
+    "babel-cli": "6",
+    "babel-preset-es2015": "6"
+  }
 }