プロジェクト作成とハローワールド

$ mkdir linebot
$ cd linebot 
$ npm init -y

$ npm i @line/bot-sdk express 

$ npm install dotenv --save

$ touch index.js $$ .env

$ code .

index.js

'use strict';

const express = require('express');
const line = require('@line/bot-sdk');
const PORT = process.env.PORT || 3000;
const dotenv = require('dotenv')
dotenv.config()

const config = {
    channelAccessToken: process.env.CHANNEL_ACCESS_TOKEN,
  channelSecret: process.env.CHANNEL_SECRET
};

const app = express();

app.get('/', (req, res) => res.send('Hello（GET)')); 
app.post('/webhook', line.middleware(config), (req, res) => {
    console.log(req.body.events);

     if(req.body.events[0].replyToken === '00000000000000000000000000000000' && req.body.events[1].replyToken === 'ffffffffffffffffffffffffffffffff'){
        res.send('Hello!(POST)');
        console.log('疎通確認用');
        return; 
    }

    Promise
      .all(req.body.events.map(handleEvent))
      .then((result) => res.json(result));
});

const client = new line.Client(config);

function handleEvent(event) {
  if (event.type !== 'message' || event.message.type !== 'text') {
    return Promise.resolve(null);
  }

  return client.replyMessage(event.replyToken, {
    type: 'text',
    text: event.message.text 
  });
}

app.listen(PORT);
console.log(`Server running at ${PORT}`);

.env.sample

CHANNEL_ACCESS_TOKEN = "xxxxxxxxxxxxxxxxxxx"
CHANNEL_SECRET = "xxxxxxxxxxxxxx"
BASE_URL = 'xxxxxxxxxxxxx.ngrok.io'

$ ngrok http 3000

BASE_URLの書き換え

$ node index.js

webhookURLの設定

https://xxxxxxxxxxxxxxxxxx.ngrok.io/webhook