reactjs | 易学教程

Add React elements dynamically depending on the content height

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问题 I have a blog post page, which have a component named PostContent that contains the text of the post. What I want to achieve is to dynamically add some content among the paragraphs of this PostContent depending on its length. I will do that by introducing the mentioned content with a distance of 1.5x viewport's height. The problem I have is I cannot calculate the distance. I am using https://www.npmjs.com/package/html-react-parser but I cannot access to the offsetHeight property of the DOM

How to get Image Url from local Json file in React.js

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问题 I want to be able to display images from a local folder by getting the URL from JSON file. So far I've tried : src={require(blog.imUrl)} src={blog.imgUrl} src={require( ${blog.imgUrl} )} Errors i am getting when I use require : Error: Cannot find module '../../images/safe-image.jpeg' import { useHistory } from 'react-router-dom'; import { Col, Row, Container, Image } from 'react-bootstrap'; import blogArticles from './blog.json'; import './BlogCard.css'; export default function BlogCard() {

React SPA - GTM Analytics React-Helmet Previous Page Title

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问题 I am using Google Tag Manager to push pageview events to the datalayer for Analytics tracking. This is happening in componentDidMount() (and sometimes componentWillReceiveProps() if I am listening for query string parameter changes with the location prop using withRouter). I am using react-helmet to dynamically update my title and other tags as components change. I have noticed an issue that I am getting the improper page title in Analytics. It's frequently showing the page title of the

How to redirect in React

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问题 I have a react app that acts as a dashboard and displays links for different React applications. Users can select the application by clicking a button. In short I need to redirect to a different URL based on user selection. In the sample code below, trying to redirect to a URL using withRouter. However its giving the below error: TypeError: Cannot read property 'push' of undefined I am using React 15.6.1. index.js render( <BrowserRouter> <Home /> </BrowserRouter>, document.getElementById('app

如何在react中处理onKeyPress事件

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参考： https://stackoverflow.com/questions/27827234/how-to-handle-the-onkeypress-event-in-reactjs 以前过时的做法：使用keyCode var Test = React.createClass({ add: function(event){ if(event.keyCode == 13){ alert('Adding....'); } }, render: function(){ return( <div> <input type="text" id="one" onKeyPress={this.add} /> </div> ); } }); React.render(<Test />, document.body); 现在建议的做法：使用语义化的key handleKeyPress = (event) => { if(event.key === 'Enter'){ console.log('enter press here! ') } } render: function(){ return( <div> <input type="text" id="one" onKeyPress={this.handleKeyPress} /> </div> ); } 来源： oschina 链接：

Async useState leading to undefined element down the hierarchy

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问题 Setup/Scenario I am using twitter api to fetch data and rendering it in twitter card using react-native-socials. The tweet data ( JSON ) is stored and served through my backend and rendered in the app. I am using a Flatlist to render this data. Problem It's working fine for the first 3 loads, I am using pullToRefresh in flatlist to do a network call to get new data. But when I try the 4th time it gets an undefined element. I've replaced the Twitter element ( from react-native-socials lib )

Async useState leading to undefined element down the hierarchy

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Async useState leading to undefined element down the hierarchy

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Why NextJS using Docker container did not reload after changed code for dev environment?

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问题 I'm trying to run the NextJS on a Docker container using Dockerfile and running via docker-compose, after I changed my code in a JS file (such as index.js) the Next server did not reload. But when I've tried to run outside without using Docker (by executing the "npm run dev" command directly) the Next server did reload smoothly. I've also tried to run the server by "nodemon" command (inside a container), it did not make it either. Dockerfile: FROM node:10.14.2-alpine COPY . /home/next_app

Why NextJS using Docker container did not reload after changed code for dev environment?

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