// When a button is pressed, an Event occurs - deal with it
// directly right here in an anonymous function, where all the
// necessary variables are present and can be referenced directly
$("#myButton").click(function(){
if ($("#myTextField").val() != $(this).val())
alert("Field must match button text");
});
实际上，服务器端和客户端没有任何区别。没错，这没有按钮点击操作，也没有向文本字段键入的操作，但在一个更高的层面上，事件正在 发生。一个连接被建立，这是一个事件！数据通过连接进行接收，这也是一个事件！数据通过连接停止，这还是一个事件！
为什么这种设置类型对 Node 很理想？JavaScript 是一种很棒的事件驱动编程语言，因为它允许使用匿名函数和闭包，更重要的是，任何写过代码的人都熟悉它的语法。事件发生时调用的回调函数可以在捕获事件处进行编写。这样可以使代码容易编写和维护，没有复杂的面向对象框架，没有接口，没有过度设计的可能性。只需监听事件，编写一个回调函数，其他事情都可以交给系统处理！
示例 Node 应用程序
最后，我们来看一些代码！让我们将讨论过的所有内容汇总起来，从而创建我们的第一个 Node 应用程序。我们已经知道，Node 对于处理高流量应用程序很理想，所以我们将创建一个非常简单的 Web 应用程序，一个为实现最快速度而构建的应用程序。下面是 “老板” 交代的关于我们的样例应用程序的具体要求：创建一个随机数字生成器 RESTful API。这个应用程序应该接受一个输入：一个名为 “number” 的参数。然后，应用程序返回一个介于 0 和该参数之间的随机数字，并将生成的数字返回给调用者。由于 “老板” 希望该应用程序成为一个广泛流行的应用程序，因此它应该能处理 50,000 个并发用户。我们来看看以下代码：
清单 2. Node 随机数字生成器
复制代码 代码如下:
// these modules need to be imported in order to use them.
// Node has several modules. They are like any #include
// or import statement in other languages
var http = require("http");
var url = require("url");
// The most important line in any Node file. This function
// does the actual process of creating the server. Technically,
// Node tells the underlying operating system that whenever a
// connection is made, this particular callback function should be
// executed. Since we're creating a web service with REST API,
// we want an HTTP server, which requires the http variable
// we created in the lines above.
// Finally, you can see that the callback method receives a 'request'
// and 'response' object automatically. This should be familiar
// to any PHP or Java programmer.
http.createServer(function(request, response) {
// The response needs to handle all the headers, and the return codes
// These types of things are handled automatically in server programs
// like Apache and Tomcat, but Node requires everything to be done yourself
response.writeHead(200, {"Content-Type": "text/plain"});
// Here is some unique-looking code. This is how Node retrives
// parameters passed in from client requests. The url module
// handles all these functions. The parse function
// deconstructs the URL, and places the query key-values in the
// query object. We can find the value for the "number" key
// by referencing it directly - the beauty of JavaScript.
var params = url.parse(request.url, true).query;
var input = params.number;
// These are the generic JavaScript methods that will create
// our random number that gets passed back to the caller
var numInput = new Number(input);
var numOutput = new Number(Math.random() * numInput).toFixed(0);
// Write the random number to response
response.write(numOutput);
// Node requires us to explicitly end this connection. This is because
// Node allows you to keep a connection open and pass data back and forth,
// though that advanced topic isn't discussed in this article.
response.end();