来自节点的错误-js mysql连接未保存到数组

var connections = [];

var mysql = require('mysql');

var connection = mysql.createConnection({
  host: 'localhost',
  user: 'username',
  password: 'password',
  database: 'database_name'
});

connection.connect(function(err) {
  if (err) {
    console.error('Error connecting to MySQL: ' + err.stack);
    return;
  }

  console.log('Connected to MySQL as id ' + connection.threadId);

  // 将连接保存到数组中
  connections.push(connection);
});

// 关闭连接
connection.end(function(err) {
  if (err) {
    console.error('Error closing MySQL connection: ' + err.stack);
    return;
  }

  console.log('MySQL connection closed');

  // 从数组中删除连接
  var index = connections.indexOf(connection);
  if (index > -1) {
    connections.splice(index, 1);
  }
});