npm install babel-cli -g

{
 "presets": []
}

const arr = [1, 2, 3];
arr.map(item => item + 1);

{
 "presets": []
}

babel 1.js -o dist.js

npm install --save-dev babel-preset-es2015 babel-preset-stage-0

{
 "presets": [
 "es2015",
 "stage-0"
 ]
}

babel 1.js -o dist.js

var arr = [1, 2, 3];
arr.map(function (item) {
 return item + 1;
});

async function start() {
 const data = await test();
 console.log(data);
}
function test() {
 return new Promise((resolve, reject) => {
 resolve('ok');
 })
}

'use strict';
var start = function () {
 var _ref = _asyncToGenerator( /*#__PURE__*/regeneratorRuntime.mark(function _callee() {
 var data;
 return regeneratorRuntime.wrap(function _callee$(_context) {
  while (1) {
  switch (_context.prev = _context.next) {
   case 0:
   _context.next = 2;
   return test();

   case 2:
   data = _context.sent;

   console.log(data);

   case 4:
   case 'end':
   return _context.stop();
  }
  }
 }, _callee, this);
 }));
 return function start() {
 return _ref.apply(this, arguments);
 };
}();
function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }

function test() {
 return new Promise(function (resolve, reject) {
 resolve('ok');
 });
}

export default function say() {
 console.log('2333');
}

import say from './util';
say();

babel demo -d dist

npm install --save-dev babel-preset-env

{
 "presets": [
  ["env", {
  "targets": {
   "node": "current"
  }
  }]
 ]
 }

class F {
 say() {
  
 }
}
const a = 1;

babel 1.js -o dist.js

"use strict";
class F {
 say() {}
}
const a = 1;

npm install --save-dev babel-register

npm install koa --save

export function getMessage() {
 return new Promise((resolve, reject) => {
  resolve('Hello World!');
 })
}

import Koa from 'koa';
import { getMessage } from './util'
const app = new Koa();
app.use(async ctx => {
 const data = await getMessage();
 ctx.body = data;
});
app.listen(3000);

node app

require("babel-register");
require("./app.js");

node index

babel app -d dist

node app