December 2017
Intermediate to advanced
329 pages
6h 9m
Chinese
Content preview from React学习手册
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186
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第
8
章
{ type: "ADD_COOLOR" }
上述拼写错误将会在我们的应用程序中导致一个
bug
。这种错误通常并不会触发任何
警告信息，用户只是不会看到对
State
数据的预期变更。如果用户犯了类似错误，那么
它们是很难察觉的。这时候常数就可以帮上大忙了：
import C from "./constants"
{ type: C.ADD_COLOR }
这种方法声明了相同的
Action
，不过使用了一个
JavaScript
常量来代替字符串。
JavaScript
变量中的拼写错误将会导致浏览器抛出异常。将
Action
定义为常量也使得用
户能够充分利用
IDE
工具的智能提示和代码自动补全功能。当输入常量的首个或者前
两个字母时，
IDE
将会为用户自动补全其余的部分。常量的使用并不是必需的，但是
采用这种编码习惯也不失为一个好的主意。
Action
类型命名规范
Action
类型，比如
ADD_COLOR
或者
RATE_COLOR
，只是字符串，因此从技术的角度
来说，用户可以随意地对一个
Action
进行命名。通常来说，
Action
类型是由大
写字母组成的，并使用下划线代替空格。同时用户还需要明确说明该
Action
的
目的。
Action
的有效载荷数据
Action
是以
JavaScript
语法的形式提供变更某个
State
所需的一系列指令的。大部分
State
变更还需要一些数据。哪些记录应该被移除？某个新记录中应该添加哪些新的信息？
我们将此类数据称为
Action
的有效载荷。比如，当我们分发了一个类似
RATE_COLOR ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.