use ES.next code in the readme

README.md

@@ -2,7 +2,7 @@
 
 [![NPM version](https://img.shields.io/npm/v/wrap-promise.svg)](https://www.npmjs.com/package/wrap-promise)
 [![Bower version](https://img.shields.io/bower/v/wrap-promise.svg)](https://github.com/shinnn/wrap-promise/releases)
-[![Build Status](https://img.shields.io/travis/shinnn/wrap-promise.svg)](https://travis-ci.org/shinnn/wrap-promise)
+[![Build Status](https://travis-ci.org/shinnn/wrap-promise.svg?branch=master)](https://travis-ci.org/shinnn/wrap-promise)
 [![Build status](https://ci.appveyor.com/api/projects/status/hs2fbpxk34gbteub?svg=true)](https://ci.appveyor.com/project/ShinnosukeWatanabe/wrap-promise)
 [![Coverage Status](https://img.shields.io/coveralls/shinnn/wrap-promise.svg?label=cov)](https://coveralls.io/r/shinnn/wrap-promise)
 [![Dependency Status](https://img.shields.io/david/shinnn/wrap-promise.svg?label=deps)](https://david-dm.org/shinnn/wrap-promise)
@@ -15,44 +15,36 @@ Like `new Promise()`, but prevents implicit rejection
 ### Using the native `new Promise()`
 
 ```javascript
-var fs = require('fs');
+const fs = require('fs');
 
-new Promise(function(resolve, reject) {
+new Promise((resolve, reject) => {
   // Node's fs.readFile throws a type error when the first argument is not a string.
 
-  fs.readFile(123, function(err, buf) { // doesn't throw, but calls `onRejected` function
+  fs.readFile(123, (err, buf) => { // doesn't throw, but calls `onRejected` function
     if (err) {
       reject(err);
       return;
     }
     resolve(buf);
   });
-}).catch(onRejected);
-
-function onRejected() {
-  console.log('This function should be called.');
-}
+}).catch(() => console.log('This function should be called.'));
 ```
 
 ### Using *wrap-promise*
 
 ```javascript
-var fs = require('fs');
-var wrapPromise = require('wrap-promise');
+const fs = require('fs');
+const wrapPromise = require('wrap-promise');
 
-wrapPromise(function(resolve, reject) {
-  fs.readFile(123, function(err, buf) { // doesn't call `onRejected` but throws immediately
+wrapPromise((resolve, reject) => {
+  fs.readFile(123, (err, buf) => { // doesn't call `onRejected` but throws immediately
     if (err) {
       reject(err);
       return;
     }
     resolve(buf);
   });
-}).catch(onRejected);
-
-function onRejected() {
-  console.log('This function should not be called.');
-}
+}).catch(() => console.log('This function should not be called.'));
 ```
 
 [According to the Promise specification](https://github.com/domenic/promises-unwrapping/blob/2a942729249c2490507a1ae6c9a24f8fa11a98e4/reference-implementation/lib/testable-implementation.js#L293-L297), a `promise` will [be rejected implicitly when an error is thrown in the constructor callback](http://www.html5rocks.com/en/tutorials/es6/promises/#toc-exceptions-and-promises). The only (and the biggest) difference is that *wrap-promise* immediately throws an error in such a case.
@@ -76,7 +68,7 @@ bower install wrap-promise
 #### [Duo](http://duojs.org/)
 
 ```javascript
-var wrapPromise = require('shinnn/wrap-promise');
+const wrapPromise = require('shinnn/wrap-promise');
 ```
 
 ### Standalone
@@ -88,7 +80,7 @@ var wrapPromise = require('shinnn/wrap-promise');
 ### wrapPromise(*fn*)
 
 *fn*: `Function`  
-Return: `Object` ([Promise](http://promisesaplus.com/))
+Return: `Object` ([Promise](https://promisesaplus.com/))
 
 It can be used in the same way as `new Promise()` but [`new` operator](http://www.ecma-international.org/ecma-262/5.1/#sec-11.2.2) is not needed.
 
@@ -106,7 +98,7 @@ By default it uses the global `Promise` constructor if available, otherwise it [
 If you don't need the fallback, use [`no-fallback.js`](https://github.com/shinnn/wrap-promise/blob/master/no-fallback.js) instead. (Useful for [Browserify](http://browserify.org/))
 
 ```javascript
-var wrapPromise = require('wrap-promise/no-fallback');
+const wrapPromise = require('wrap-promise/no-fallback');
 ```
 
 #### On non-CommonJS environment