class MyComponent extends Component { constructor(props){ super(props) this.myInput = React.createRef() } componentDidMount () { console.log(this.myInput.current.offsetWidth) } render () { return ( // new way – as of React@16.3 <div ref={this.myInput}>some elem</div> // legacy way // <div ref={(ref) => this.myInput = ref}>some elem</div> ) } }
Create-React-App has a very interesting setup. I started digging in the package.json npm script start “start”: “react-scripts start” That takes me to their binary react-scripts under node_modules/.bin I’ll post the relevant stuff here. switch (script) { case ‘build’: case ‘eject’: case ‘start’: case ‘test’: { const result = spawn.sync( ‘node’, [require.resolve(‘../scripts/’ + script)].concat(args), { stdio: … Read more
From Jest’s command-line options docs –verbose Display individual test results with the test suite hierarchy. So running jest –verbose Will print all the names in describe, it, test blocks. If you’re running tests with yarn, you can do yarn test –verbose If you’re running tests with npm, you can do npm test — –verbose If … Read more
The short version: avoid refs. They’re bad for maintainability, and lose a lot of the simplicity of the WYSIWYG model render provides. You have a form. You need to add a button that resets the form. refs: manipulate the DOM render describes how the form looked 3 minutes ago state setState render describes how the … Read more
You need to specify the attribute exact for your indexRoute, otherwise for even /details route it will still match with / . Also try to import Route from react-router-dom import React from “react”; import ReactDOM from “react-dom”; import { BrowserRouter, Route } from ‘react-router-dom’; import Users from “./components/Users”; import Details from “./components/Details”; ReactDOM.render(( <BrowserRouter> <div> … Read more
A simple example would be an app that collects input data from the user and then uses Ajax to upload said data to a database. Here’s a simplified example (haven’t run it – may have syntax errors): export default class Task extends React.Component { constructor(props, context) { super(props, context); this.state = { name: “”, age: … Read more
You have to dispatch after the async request ends. This would work: export function bindComments(postId) { return function(dispatch) { return API.fetchComments(postId).then(comments => { // dispatch dispatch({ type: BIND_COMMENTS, comments, postId }); }); }; }
Webpack doesn’t know to resolve .jsx files implicitly. You can specify a file extension in your app (import App from ‘./containers/App.jsx’;). Your current loader test says to use the babel loader when you explicitly import a file with the jsx extension. or, you can include .jsx in the extensions that webpack should resolve without explicit … Read more
The other answer assumes you are using external pre-built files from react, and while correct that is not how most folks are going to or should consume React as a package. Moreover, at this point most every React library and package also relies on the same convention to toggle dev time helpers off during production. … Read more
You can mock the module so it returns spies and import it into your test: import {navigationEnabled, guidanceEnabled} from ‘../../../magic/index’ jest.mock(‘../../../magic/index’, () => ({ navigationEnabled: jest.fn(), guidanceEnabled: jest.fn() })); Then later on you can change the actual implementation using mockImplementation navigationEnabled.mockImplementation(()=> true) //or navigationEnabled.mockReturnValueOnce(true); and in the next test navigationEnabled.mockImplementation(()=> false) //or navigationEnabled.mockReturnValueOnce(false);