diff --git a/.babelrc b/.babelrc
index d6bfc30..eec6ce6 100644
--- a/.babelrc
+++ b/.babelrc
@@ -3,12 +3,14 @@
         [
             "env",
             {
+                "useBuiltIns": "entry",
                 "modules": false,
                 "targets": {
                     "browsers": [
-                        "> 1%",
+                        "> 0.5%",
                         "last 2 versions",
-                        "not ie <= 8"
+                        "Firefox ESR",
+                        "not dead"
                     ]
                 }
             }
diff --git a/package.json b/package.json
index 66ae5c2..dd78813 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
   },
   "dependencies": {
     "@octokit/rest": "^15.6.2",
+    "babel-polyfill": "^6.26.0",
     "bottleneck": "^2.3.1",
     "octonode": "^0.9.2"
   },
diff --git a/src/gh.ts b/src/gh.ts
index 8703b31..db3f968 100644
--- a/src/gh.ts
+++ b/src/gh.ts
@@ -73,7 +73,7 @@ interface ResponseWithMetaLink {
 
 interface ResponseWithDataArrayAndMeta<T>
   extends ResponseWithDataArray<T>,
-  ResponseWithMetaLink { }
+    ResponseWithMetaLink {}
 
 interface ResponseFromGetUserRepo extends ResponseWithMetaLink {
   data: RepoFromGetUserRepo[];
@@ -163,7 +163,7 @@ interface RepoNameWithParentRepo {
 
 interface RepoNameWithBranchesAndParent
   extends RepoNameWithBranches,
-  RepoNameWithParentRepo { }
+    RepoNameWithParentRepo {}
 
 const username = 'rousan';
 
@@ -204,13 +204,13 @@ async function fetchRepoNameWithBranches(
 
   const branchesResponse: ResponseWithDataArray<
     BranchFromGetBranches
-    > = await paginate((tmpFirstParam: Octokit.ReposGetBranchesParams): Promise<
+  > = await paginate((tmpFirstParam: Octokit.ReposGetBranchesParams): Promise<
+    ResponseFromGetBranches
+  > => {
+    return (octokit.repos.getBranches(tmpFirstParam) as any) as Promise<
       ResponseFromGetBranches
-      > => {
-      return (octokit.repos.getBranches(tmpFirstParam) as any) as Promise<
-        ResponseFromGetBranches
-        >;
-    }, params);
+    >;
+  }, params);
 
   return {
     repoName,
@@ -319,31 +319,31 @@ async function fetchUserIsNotContributor(
 
   const responseFromGetContributors: ResponseWithDataArray<
     OwnerFromGetContributors
-    > = await paginate(
-      async (
-        tmpFirstParam: Octokit.ReposGetContributorsParams
-      ): Promise<ResponseWithDataArrayAndMeta<OwnerFromGetContributors>> => {
-        // Modify getContributors to return empty contributor data array instead of undefined for empty repos
-        const response = await ((octokit.repos.getContributors(
-          tmpFirstParam
-        ) as any) as Promise<ResponseFromGetContributors>);
+  > = await paginate(
+    async (
+      tmpFirstParam: Octokit.ReposGetContributorsParams
+    ): Promise<ResponseWithDataArrayAndMeta<OwnerFromGetContributors>> => {
+      // Modify getContributors to return empty contributor data array instead of undefined for empty repos
+      const response = await ((octokit.repos.getContributors(
+        tmpFirstParam
+      ) as any) as Promise<ResponseFromGetContributors>);
 
-        let dataNormalized = response.data;
-        if (dataNormalized === undefined) {
-          dataNormalized = [];
-        }
+      let dataNormalized = response.data;
+      if (dataNormalized === undefined) {
+        dataNormalized = [];
+      }
 
-        const responseNormalized: ResponseWithDataArrayAndMeta<
-          OwnerFromGetContributors
-          > = {
-          data: dataNormalized,
-          meta: response.meta,
-        };
+      const responseNormalized: ResponseWithDataArrayAndMeta<
+        OwnerFromGetContributors
+      > = {
+        data: dataNormalized,
+        meta: response.meta,
+      };
 
-        return responseNormalized;
-      },
-      params
-    );
+      return responseNormalized;
+    },
+    params
+  );
 
   const contributors = responseFromGetContributors.data;
 
@@ -369,7 +369,7 @@ export async function fetchUnusedForkedRepos() {
     ): Promise<ResponseFromGetUserRepo> => {
       return (octokit.repos.getForUser(tmpFirstParam) as any) as Promise<
         ResponseFromGetUserRepo
-        >;
+      >;
     },
     params
   );
@@ -514,7 +514,6 @@ export async function fetchUnusedForkedRepos() {
   return unusedRepoNames;
 }
 
-
 export function runMain() {
   fetchUnusedForkedRepos().then(unusedRepoNames => {
     // tslint:disable-next-line:no-console
diff --git a/src/index.ts b/src/index.ts
index b9ed9bb..20e5a8e 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,10 +1,11 @@
+import 'babel-polyfill';
 import { Greeter } from './greeter';
 // tslint:disable-next-line:ordered-imports
 import { fetchUnusedForkedRepos, runMain } from './gh';
 export * from './greeter';
 
 // tslint:disable-next-line:only-arrow-functions
-(function (currentWindow: Window) {
+(function(currentWindow: Window) {
   // execute when load index.js
 
   // tslint:disable-next-line:no-console
diff --git a/todo.js b/todo.js
index 93d3c27..3dd9f25 100644
--- a/todo.js
+++ b/todo.js
@@ -13,4 +13,4 @@
 
 /** 
 * @todo In webpack, enable uglify for minifying
-*/ 
\ No newline at end of file
+*/ 
diff --git a/webpack.config.js b/webpack.config.js
index c37c10f..876d4fd 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -22,10 +22,10 @@ module.exports = {
     ]
   },
   plugins: [
-    new webpack.optimize.UglifyJsPlugin({
-      include: /\.min\.js$/,
-      minimize: true
-    }) , 
+    // new webpack.optimize.UglifyJsPlugin({
+    //   include: /\.min\.js$/,
+    //   minimize: true
+    // }) , 
     new CopyWebpackPlugin([
       { from: 'demo/index.html', to: 'dist/' }
     ])
diff --git a/yarn.lock b/yarn.lock
index 66c9058..e52f7d0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -792,6 +792,14 @@ babel-plugin-transform-strict-mode@^6.24.1:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
+babel-polyfill@^6.26.0:
+  version "6.26.0"
+  resolved "https://registry.yarnpkg.com/babel-polyfill/-/babel-polyfill-6.26.0.tgz#379937abc67d7895970adc621f284cd966cf2153"
+  dependencies:
+    babel-runtime "^6.26.0"
+    core-js "^2.5.0"
+    regenerator-runtime "^0.10.5"
+
 babel-preset-env@^1.6.1:
   version "1.7.0"
   resolved "https://registry.yarnpkg.com/babel-preset-env/-/babel-preset-env-1.7.0.tgz#dea79fa4ebeb883cd35dab07e260c1c9c04df77a"
@@ -4660,6 +4668,10 @@ regenerate@^1.2.1:
   version "1.4.0"
   resolved "https://registry.yarnpkg.com/regenerate/-/regenerate-1.4.0.tgz#4a856ec4b56e4077c557589cae85e7a4c8869a11"
 
+regenerator-runtime@^0.10.5:
+  version "0.10.5"
+  resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.10.5.tgz#336c3efc1220adcedda2c9fab67b5a7955a33658"
+
 regenerator-runtime@^0.11.0:
   version "0.11.1"
   resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.11.1.tgz#be05ad7f9bf7d22e056f9726cee5017fbf19e2e9"