on(type,[function(){...}])监听通道状态

on(‘close’, function() {…})

on(‘error’, function(err) {…})

on(‘return’, function(msg) {…})

on(‘drain’, function() {…})

• close，channel关闭
• error，channel异常
• return，？？？
• drain，？？？

  (async () => {
  try {
    const connection = await amqp.connect(url)
    const channel = await connection.createChannel();
    const queue = 'hello';
    const msg = 'Hello World!';
    await channel.assertQueue(queue, { durable: false });
    await channel.sendToQueue(queue, Buffer.from(msg));
    console.log(" [x] Sent %s", msg);
    channel.on('close', () => {
      console.log('channel.on close')
    })
    channel.on('error', (err) => {
      console.log('channel.on error:', err)
    })
    channel.on('return', (msg) => {
      console.log('channel.on return:', msg)
    })
    channel.on('drain', () => {
      console.log('channel.on drain')
    })
    await channel.close();
    setTimeout(async () => await connection.close(), 500)
  } catch (e) {
    console.log(e)
  }
  })()