chaiyu2002

它们在和中被触发。触发时你可以在testrpc的输出中看到日志。要监听事件，你可以使用web.js监听器(listener)。在写本文时我还不能在truffle测试中记录事件，但是在应用中没问题：

They are triggered in the process. You can see logs in the output of testrpc at the time of triggering. To listen to an event, you can use the web.js listening device (listener). I can't record an event in a truffle test at the time of writing, but it's okay in the application:

总的来说，使用事件和过滤器的组合比检查变量消耗的Gas更少，因而在验证正式网络的交易运行结果时非常有用。

In general, the combination of events and filters is less expensive than the Gas used to check variables and is therefore very useful in validating the transaction results of the official network.

下面的段落会假设你没有网页开发经验。

The paragraph under assumes that you do not have web page development experience.

上面编写的测试用例用到的都是在前端界面中也可以用的方法。你可以把前端代码放到目录中，运行之后它们会和合约配置信息一起编译输出到目录。在开发时可以使用命令在有任何变动时自动编译输出到目录。然后在浏览器中刷新页面即可看到目录中的最新内容。（可以启动一个基于目录的网页服务器。）

The tests above are used for methods that can also be used in front-end interfaces. You can place front-end codes in the directory, and then they are translated into the directory together with the contractual configuration information. You can use the command to automatically edit the output to the directory at the time of development when any changes are made. The latest contents of the directory can then be seen in a new page on the browser. (A directory-based web server can be activated.)

目录中有一些样板文件帮助你开始：

There are some templates in the directory that help you start:

会加载：

Will be loaded:

因此我们只需要添加代码到就可以了。

So we just have to add code to it.

默认的会在浏览器的console(控制台)中输出一条”Hello from Truffle!”的日志。在项目根目录中运行，然后在浏览器中打开文件，再打开浏览器的console就可以看到。（大部分浏览器例如Chrome中，单击右键 -> 选择Inspect Element然后切换到Console即可。）

The default output of a log "Hello from Trade!" in the browser's console! Runs in the project root directory, then opens the file in the browser and then opens the browser's console. (Most browsers, for example, in Chhome, click right -> select Inspect Regulation and then switch to Console.)

在中，添加一个在页面加载时会运行的调用。下面的代码会确认web3.js已经正常载入并显示所有可用的账户。（注意：你的testrpc节点应该保持运行。）

In which, add a call that will run when the page is loaded. The code below confirms that web3.js is properly loaded and displays all available accounts. (Note: your testrpc node should remain running.)

看看你的浏览器console中看看是否打印出了一组账户地址。

Check your browser console to see if you printed out a set of account addresses.

现在你可以从中复制一些代码过来（去掉只和测试有关的断言），将调用返回的结果输出到console中以确认代码能工作。下面是个例子：

Now you can copy some of the codes from them (remove only the test-related assertions) and export the returned results to the console to confirm that the code works. Here's an example:

上面的代码应该输出如下：

The code above should be exported as follows:

(console输出的warning信息可忽略。)

(Console output of warning information is negligible.

现在起你就可以使用你喜欢的任何前端工具，jQuery, ReactJS, Meteor, Ember, AngularJS，等等等等，在目录中构建可以与以太坊智能合约互动的DApp界面了！接下来我们给出一个极其简单基于jQuery的界面作为示例。

From now on, you can use any front-end tool you like, jQuery, ReactJS, Meteor, Ember, AngularJS, etc., and so on, to build a Dapp interface in the directory that can interact with an Ethernomy smart contract. Let us then give an example of an extremely simple jQuery-based interface.

通过界面测试了智能合约之后我意识到最好加入检查以保证相同的用户不能注册两次。另外由于现在是运行在testrpc节点上，速度很快，最好是切换到geth节点并确认交易过程依然能及时响应。否则的话界面上就应该显示提示信息并且在处理交易时禁用相关的按钮。

After testing the smart contract through the interface, I realized that it would be better to include a check to ensure that the same user could not register twice. And since it is now running on the testrpc node, fast, it is better to switch to the geth node and confirm that the transaction is still responsive in time. Otherwise, the interface should show the alert information and disable the relevant buttons when processing the transaction.

然后把整个, 流程重来一遍。

And then put the whole, the process over and over again.

教程到此结束！ 最后一章我们仅仅学习了一套工具集，主要是Truffle和testrpc. 要知道即使在ConsenSys内部，不同的开发者使用的工具和框架也不尽相同。你可能会发现更适合你的工具，这里所说的工具可能很快也会有改进。但是本文介绍的工作流程帮助我走上了DApp开发之路。