redux | 易学教程

《深入浅出React和Redux》(2)

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Redux是Flux理念的一种实现。关于Flux理念可以通过类比MVC模式来做简单理解。 MVC模式中，用户请求先到达Controller，由Controller调用Model获得数据，然后把数据交给View，按照这种模式，MVC应该也是一个controller->model->view的单向数据流，但是，在实际应用中，由于种种原因，往往会让view直接操作Model，随着应用的演进、逻辑变得越来约复杂，view与model之间的关系就会变得错综复杂、难以维护。在MVC中让View和Model直接对话就是灾难。 Flux理念可以简单看作是对MVC添加了更加严格的数据流限制。 Flux框架随React一同被Fackbook推出，但在Dan Abramov创建了Redux后，Redux已经替代了Flux。基本原则 Flux的基本原则是“单向数据流”, Redux在此基础上强调三个基本原则：唯一数据源（Single Source of Truth），应用的状态数据应该只存储在唯一的一个Store上，它是树形结构，每个组件往往只是用树形对象上一部分的数据，而如何设计Store上状态的结构，就是Redux应用的核心问题。保持状态只读（State is read-only），不能直接修改store状态，必须要通过派发action对象的方式来进行。数据改变只能通过纯函数完成

Guidelines to build a secure JWT authentication process?

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问题 This bounty has ended . Answers to this question are eligible for a +50 reputation bounty. Bounty grace period ends in 3 hours . AndreaCostanzo1 wants to draw more attention to this question. Recently I needed to build a simple REST API and I read different articles on best practices to reduce as far as possible the vulnerabilities of my web app. Searching online I found different tutorials on how to implement JWT tokens, every one different in some aspects, and I couldn't find a well

2020年，大前端最为理想的技术体系

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大前端时代现在的前端，已经不是只能制作 H5 网页，发送 Ajax 请求这样比较简单的岗位。一个真正意义上的大前端，可以同时开发跨平台桌面、移动端，小程序，中间件编写、 docker 自动化、云端服务器部署等。写这篇文章的起因最近很多朋友在吐槽，社区重复出现了很多篇 10分钟精通**技术，万字长文彻底了解 ES 系列等文章，其实技术分享并没有什么问题，只是这样反复的技术文章出现说明，目前的前端技术栈，已经基本稳固，再有出现，短期难有爆发。关键是很多人询问，该怎么学习前端技术，工作经验很少等等。可是我的工作经验其实也很短呢。刚好今晚与一起做即时通讯的后端同事在谈论技术，于是想写一篇关于 2020 年前端技术栈的文章。以下是作者本人推荐掌握的技术栈：首先是：原生基础三剑客： JavaScript 、TypeScript 、 Node.js 抛出一个问题：是不是有了React、Vue等框架就不需要Dom操作，不需要了解JQuery了？答案：实现越复杂的功能， DOM 操作越重要，框架底层也是 DOM 操作。只不过加了些中间层（ diff 算法等），想深入了解的可以 gitHub 看我的仓库 mini-react ，自己实现的 React 框架～ https: //github.com/JinJieTan/mini-react JavaScript 的学习：

react redux with asynchronous fetch

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问题 I am using react redux, and trying to call rest-api, and return the data. The fetch is asynchronous, and I need to return value only when the fetch is finished. I tried the following, but this didn't work properly (there is no 'wait' on the line that is with asterisks) - What shall I do? Code: ----- var _getData = function() { return new Promise((resolve, reject) => { let options = { method: 'GET', } let _url = "my web return json"; fetch(_url, options) .then(response => response.json(). then

React Redux onBlur event not firing in Safari and Firefox

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问题 This seems to work perfectly in Chrome and Edge. I have a tooltip that needs to pop up onClick of the button, and then disappear onBlur. For some reason the onBlur event does not fire at all on Safari or Firefox. I've tried logging to the console in handleBlur and it does not get that far, it is as if onBlur does not exist in this context. class Tooltip extends Component { componentWillUnmount() { this.closeActiveTooltip(); } handleKeyPress = (event) => { if (event.keyCode === 27) { // Esc

When to use store.dispatch() in my React / Redux app?

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问题 I'm using mapDispatchToProps in my React / Redux app. function mapDispatchToProps(dispatch) { return bindActionCreators( { fetchUsers }, dispatch); } export default connect(mapStateToProps, mapDispatchToProps)(SearchBar); I have seen store.dispatch() being used inside containers, could I use that instead of mapDispatchToProps? I don't fully understand the store.dispatch() and where should I use it? 回答1: This won't work if you render your app on server because you want to have different store

When to use store.dispatch() in my React / Redux app?

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React-Redux rendering components twice on screen when redux state changes

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问题 I am trying to make a nested comments component , with reply functionality. The code works fine when no new comment is added, but whenever I dispatch the action for new-comment, the components get rendered twice on the screen(Giving, duplicate key warning). const App = () => { const dispatch = useDispatch(); const data = useSelector((gstate) => gstate.commentsReducer.comments); const struct_data = commentsMiddleware(data); // A utility function to structure the data as per my need. useEffect(

React-Redux rendering components twice on screen when redux state changes

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Flutter : How to Debug which widgets re-rendered on state change

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问题 I am using Redux with Flutter for state management. Whenever I dispatch an action, I want to know which widgets were re-rendered. Is there any way of doing it? 回答1: In flutter, whenever one widget update ; the whole widget tree repaint. So... no. But you can also introduce "repaint boundaries" manually by inserting in your tree a RepaintBoundary widget. This explicitly tells flutter to create a new painting layer for it's child (which implies memory cache). So that whenever that child updates

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