JavaScript：回调是什么鬼？ #1792

sunui · 2017-06-20T10:30:04Z

wilsonandusa · 2017-06-21T02:49:35Z

reid3290 · 2017-06-21T05:04:09Z

reid3290 · 2017-06-21T05:10:45Z

TODO/javascript-what-the-heck-is-a-callback.md


 ![](https://cdn-images-1.medium.com/max/1000/1*pWGJIKats-zuumA3RQNEWQ.jpeg)

-Callbacks — image via [unsplash](https://unsplash.com/search/call?photo=qXn5L9BqRbE)
+回调  —  题图来自 [unsplash](https://unsplash.com/search/call?photo=qXn5L9BqRbE)


破折号是不是 ——

reid3290 · 2017-06-21T05:11:51Z

TODO/javascript-what-the-heck-is-a-callback.md


-### Why do we need Callbacks?
+^ 这听起来有点罗嗦，让我们来看一些例子来简化一下。


罗嗦 => 啰嗦

reid3290 · 2017-06-21T05:15:44Z

TODO/javascript-what-the-heck-is-a-callback.md


-A callback is important here because we need to wait for a response from the server before we can move forward in our code. We don’t know if our API request is going to be successful or not so after sending our parameters to search/tweets via a get request, we wait. Once Twitter responds, our callback function is invoked. Twitter will either send an `err` (error) object or a `response` object back to us. In our callback function we can use an `if()` statement to determine if our request was successful or not, and then act upon the new data accordingly.
+回调在这里很重要，因为在我们的代码继续运行之前我们需要等待一个来自服务端的响应。我们并不知道 API 请求会成功或者失败，所以通过 get 向 search/tweets 发送了请求参数以后，我们要等待。一旦 Twitter 响应，我们的回调函数就被调用。Twitter 要么发送一个 `err`（error）对象，要么发送一个 `response` 对象返回给我们。在我们的回调函数中我们可以使用 `if()` 声明来区分请求是否成功，然后相应地处理新数据。


我们并不知道 API 请求会成功或者失败 => 我们并不知道 API 请求会成功还是会失败

reid3290 · 2017-06-21T05:16:28Z

TODO/javascript-what-the-heck-is-a-callback.md


-A callback is important here because we need to wait for a response from the server before we can move forward in our code. We don’t know if our API request is going to be successful or not so after sending our parameters to search/tweets via a get request, we wait. Once Twitter responds, our callback function is invoked. Twitter will either send an `err` (error) object or a `response` object back to us. In our callback function we can use an `if()` statement to determine if our request was successful or not, and then act upon the new data accordingly.
+回调在这里很重要，因为在我们的代码继续运行之前我们需要等待一个来自服务端的响应。我们并不知道 API 请求会成功或者失败，所以通过 get 向 search/tweets 发送了请求参数以后，我们要等待。一旦 Twitter 响应，我们的回调函数就被调用。Twitter 要么发送一个 `err`（error）对象，要么发送一个 `response` 对象返回给我们。在我们的回调函数中我们可以使用 `if()` 声明来区分请求是否成功，然后相应地处理新数据。


if() 声明 => if() 语句

reid3290 · 2017-06-21T05:16:45Z

TODO/javascript-what-the-heck-is-a-callback.md


-Good work! You can now (ideally) understand what a callback is and how it works. This is merely the tip of the iceberg with callbacks, there is still a lot more to learn! I publish a few articles/tutorials each week, please [enter your email here](https://docs.google.com/forms/d/e/1FAIpQLSeQYYmBCBfJF9MXFmRJ7hnwyXvMwyCtHC5wxVDh5Cq--VT6Fg/viewform) if you’d like to be added to my once-weekly email list.
+干的漂亮！你现在（理想状况下）已经理解了回调是什么,回调如何工作。这只是回调的冰山一角，记住学无止境啊！我每周都会更新一些文章/教程，如果你愿意接收每周一次的推送，[点击这里](https://docs.google.com/forms/d/e/1FAIpQLSeQYYmBCBfJF9MXFmRJ7hnwyXvMwyCtHC5wxVDh5Cq--VT6Fg/viewform)输入你的邮箱订阅吧


干的漂亮 => 干得漂亮

reid3290 · 2017-06-21T05:18:27Z

TODO/javascript-what-the-heck-is-a-callback.md


-Good work! You can now (ideally) understand what a callback is and how it works. This is merely the tip of the iceberg with callbacks, there is still a lot more to learn! I publish a few articles/tutorials each week, please [enter your email here](https://docs.google.com/forms/d/e/1FAIpQLSeQYYmBCBfJF9MXFmRJ7hnwyXvMwyCtHC5wxVDh5Cq--VT6Fg/viewform) if you’d like to be added to my once-weekly email list.
+干的漂亮！你现在（理想状况下）已经理解了回调是什么,回调如何工作。这只是回调的冰山一角，记住学无止境啊！我每周都会更新一些文章/教程，如果你愿意接收每周一次的推送，[点击这里](https://docs.google.com/forms/d/e/1FAIpQLSeQYYmBCBfJF9MXFmRJ7hnwyXvMwyCtHC5wxVDh5Cq--VT6Fg/viewform)输入你的邮箱订阅吧


输入你的邮箱订阅吧 => 输入你的邮箱订阅吧！
漏了个标点

linhe0x0 · 2017-06-21T06:55:58Z

@wilsonandusa @reid3290 好哒

reid3290 · 2017-06-21T07:19:39Z

@sunui @sqrthree 校对完毕

wilsonandusa · 2017-06-22T01:36:52Z

TODO/javascript-what-the-heck-is-a-callback.md

@@ -2,29 +2,30 @@
 > * 原文作者：[Brandon Morelli](https://codeburst.io/@bmorelli25)
 > * 译文出自：[掘金翻译计划](https://github.com/xitu/gold-miner)
 > * 译者：
-> * 校对者：


校对者：wilsonandusa

wilsonandusa · 2017-06-22T01:43:40Z

TODO/javascript-what-the-heck-is-a-callback.md

-For one very important reason — JavaScript is an event driven language. This means that instead of waiting for a response before moving on, JavaScript will keep executing while listening for other events. Lets look at a basic example:
+### 为什么我们需要回调？
+
+有一个非常重要的原因 —— JavaScript 是事件驱动的语言。这意味着，在继续运行之前，JavaScript 不会等待响应，而是在监听其他事件时继续执行。来看一个基本的例子：


"在继续运行之前，JavaScript 不会等待响应" -> "JavaScript不会因为要等待一个响应而停止当前运行"

wilsonandusa · 2017-06-22T01:49:32Z

TODO/javascript-what-the-heck-is-a-callback.md


    T.get('search/tweets', params, function(err, data, response) {
      if(!err){
-        // This is where the magic will happen
+        // 这里是魔法将要发生之处


[这里是魔法将要发生之处 ]->[这里就是神奇之处] （这样感觉通俗一点）

这里是一个将来写主要代码的地方，目前只是占位，所以目前不见得有什么神奇。打算翻译成：这里是施展魔法之处

wilsonandusa

@sqrthree @sunui 校对完成

linhe0x0 · 2017-06-22T03:10:28Z

@sunui 已经 merge 啦~ 快快麻溜发布到掘金专栏然后给我发下链接，方便及时添加积分哟。

JavaScript:回调是什么鬼？翻译初稿

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linhe0x0 mentioned this pull request Jun 21, 2017

JavaScript：回调是什么鬼？ #1785

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JavaScript：回调是什么鬼？ #1792

JavaScript：回调是什么鬼？ #1792

sunui commented Jun 20, 2017

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reid3290 commented Jun 21, 2017 •

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linhe0x0 commented Jun 22, 2017


		### Why do we need Callbacks?
		^ 这听起来有点罗嗦，让我们来看一些例子来简化一下。


		A callback is important here because we need to wait for a response from the server before we can move forward in our code. We don’t know if our API request is going to be successful or not so after sending our parameters to search/tweets via a get request, we wait. Once Twitter responds, our callback function is invoked. Twitter will either send an `err` (error) object or a `response` object back to us. In our callback function we can use an `if()` statement to determine if our request was successful or not, and then act upon the new data accordingly.
		回调在这里很重要，因为在我们的代码继续运行之前我们需要等待一个来自服务端的响应。我们并不知道 API 请求会成功或者失败，所以通过 get 向 search/tweets 发送了请求参数以后，我们要等待。一旦 Twitter 响应，我们的回调函数就被调用。Twitter 要么发送一个 `err`（error）对象，要么发送一个 `response` 对象返回给我们。在我们的回调函数中我们可以使用 `if()` 声明来区分请求是否成功，然后相应地处理新数据。


		Good work! You can now (ideally) understand what a callback is and how it works. This is merely the tip of the iceberg with callbacks, there is still a lot more to learn! I publish a few articles/tutorials each week, please [enter your email here](https://docs.google.com/forms/d/e/1FAIpQLSeQYYmBCBfJF9MXFmRJ7hnwyXvMwyCtHC5wxVDh5Cq--VT6Fg/viewform) if you’d like to be added to my once-weekly email list.
		干的漂亮！你现在（理想状况下）已经理解了回调是什么,回调如何工作。这只是回调的冰山一角，记住学无止境啊！我每周都会更新一些文章/教程，如果你愿意接收每周一次的推送，[点击这里](https://docs.google.com/forms/d/e/1FAIpQLSeQYYmBCBfJF9MXFmRJ7hnwyXvMwyCtHC5wxVDh5Cq--VT6Fg/viewform)输入你的邮箱订阅吧

JavaScript：回调是什么鬼？ #1792

JavaScript：回调是什么鬼？ #1792

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sunui commented Jun 20, 2017

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