December 2017
Intermediate to advanced
329 pages
6h 9m
Chinese
Content preview from React学习手册
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Props
、
State
和组件树
｜
129
this.setState
来修改。每次调用
setState
之后，
render
函数也会被调用，渲染新的
UI
反映
State
的变化。
根据属性初始化
State
我们可以使用传入的属性初始化
State
值。这种模式只适用于极个别必要的情况。这种
情况最常见的场景是我们创建了一个可复用的组件时，希望在不同组件树之间跨应用
调用该组件。
在使用
createClass
时，基于输入的属性初始化
State
变量的好办法是添加一个名为
componentWillMount
的方法。当加载组件时，该方法会被调用一次，并且用户可以在
该方法中调用
this.setState()
。它还可以访问
this.props
，因此用户可以读取
this.
props
中的数据辅助执行初始化
State
的操作：
const StarRating = createClass({
displayName: 'StarRating',
propTypes: {
totalStars: PropTypes.number
},
getDefaultProps() {
return {
totalStars: 5
}
},
getInitialState() {
return {
starsSelected: 0
}
},
componentWillMount() {
const { starsSelected } = this.props
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.