nodejsres.end與res.send使用區別有哪些

var express = require('express');
var app = express();
var mysql = require('mysql');
var connection = mysql.createConnection({
 host : 'localhost',
 user : 'root',
 password : 'root',
 port : 3306,
 database : 'test'
})
sql = 'select * from websites';
var arr = [];
connection.query(sql,function (err, results) {
 if (err){
 console.log(err)
 }else{
 console.log(results);
 for(var i = 0;i < results.length;i++){
 arr[i] = results[i].name;
 }
 app.get('/',function (req, res) {
 res.send(arr); //這里必須用res.send,因為有數據返回到客戶端
 })
 }
})
app.listen(3001);