redux | 易学教程

How does react decide to rerender a component

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问题 I know React has a life cycle method called shouldComponentUpdate , Which by default return true and that's how the component decides to update But How does that life cycle method gets called, When a state or props change for that component. What actually happens when we receive new props or state? When We connect a component to redux state and mapStateToProps, Are we checking for a change in values inside the component? If not, When We are looking for a change in state or props? when the

Proper use of react-redux connect

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问题 I'm new in react-redux and I was reading the documentation here https://github.com/reactjs/react-redux/blob/master/docs/api.md The documentation says that connect is defined as: connect([mapStateToProps], [mapDispatchToProps], [mergeProps], [options]) But then I see this example code import React from 'react' import { connect } from 'react-redux' import { getData } from '../actions' class Content extends React.Component { constructor(props) { super(props); } componentWillMount() { this.props

Alternative implementations of Redux source function ensureCanMutateNextListeners？

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问题 I am reading redux source, and the ensureCanMutateNextListeners function caught my eyes. The comments in the source explained very well, I can understand. However, I just felt it is a bit complex, (i.e., two listeners collections and call ensureCanMutateNextListeners before manipulate the collections), I am thinking if it is possible to simplify and still solve the original problem. The below are the two options I can think of: Original problem to solve: Keep a stable listeners when

Alternative implementations of Redux source function ensureCanMutateNextListeners？

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Download pdf file from API

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问题 I am creating a function that creates and download a pdf after button click. I am using express as backend and react/readux/axios as front. My backend runs on a different port than my front. So I am calling the API with axios, then express create the pdf and respond with sendFile. When testing my post request with postman everything works great. When i using it from my react app does not download the file express router.post('/', function( req, res, next){ var data = req.body.data options = {

Redux源码解读

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前言作为React全家桶的一份子，Redux为react提供了严谨周密的状态管理。但Redux本身是有点难度的，虽然学习了React也有一段时间了，自我感觉算是入了门，也知道redux的大概流程。但其背后诸如creatstore,applymiddleware等API背后到底发生了什么事情，我其实还是不怎么了解的，因此最近花了几天时间阅读了Redux的源码，写下文章纪录一下自己看源码的一些理解。一、源码结构（redux4.0版本） Redux是出了名的短小精悍（恩，这个形容很贴切），只有2kb大小，且没有任何依赖。它将所有的脏活累活都交给了中间件去处理，自己保持着很好的纯洁性。再加上redux作者在redux的源码上，也附加了大量的注释，因此redux的源码读起来还是不算难的。先来看看redux的源码结构，也就是src目录下的代码：源码结构其中utils是工具函数，主要是作为辅助几个核心API，因此不作讨论。（注：由于篇幅的问题，下面代码很多都删除了官方注释，和较长的warn）二、具体组成 index.js是redux的入口函数具体代码如下： 2.1 index.js import createStore from './createStore' import combineReducers from './combineReducers' import

Why does mapping state to props give undefined?

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问题 I'm having a problem with my setup of Redux. I didn't have a problem with single file of posts actions and reducers, but as soon as added a searchQueries sections, it shows only undefined values for the searchQueries props. I've tried copying it as far as I can and modifying it for the second set of actions/reducers, but I'm still ending up with undefined props in the case of searchQueries . I'm getting all the props, including the default values in the case of posts . Here's the code for

Angular 4, ng2-redux: Could not find a declaration file for module 'redux-logger'

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问题 I installed latest Angular from git clone https://github.com/angular/quickstart.git and npm i --save redux-logger redux ng2-redux Here .../node_modules/redux-logger/src/index.js there's export { defaults, createLogger, defaultLogger as logger }; Error:TS7016:Could not find a declaration file for module 'redux-logger'. '.../node_modules/redux-logger/dist/redux-logger.js' implicitly has an 'any' type. import { applyMiddleware, createStore } from 'redux'; import logger from 'redux-logger'; /

reducer.state.props is undefined in nested actions react/redux

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问题 Below are my action and reducer files - In my component state I am only seeing this.props.mainData - but others subdataOneData etc., are not being loaded in to the state - till reducer i see the right actions are being dispatched and I also see the data for sub - calls - but they are not reaching my component - I have mapStatetoprops - where I am doing New issue: as per the updated code - when i print out payload in reducer - I see maindata with the api data but SubData [{}, {}, {}] ..?

react redux-thunk component doesn't render this.props

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问题 I'm new to react and I'm trying to understand on to make async ajax request. I was able to get the request completed and the data returned added to my state, but I can't render the data to my component. Here's my setup. UserPage component import React, { Component } from 'react'; import { connect } from 'react-redux'; import { bindActionCreators } from 'redux'; import { getUsers } from '../../actions'; class User extends Component { displayName: 'User'; componentWillMount() { this.props