What is the type of the ‘children’ prop?
Just children: React.ReactNode.
reactjs
In useEffect, what’s the difference between providing no dependency array and an empty one?
It’s not quite the same. Giving it an empty array acts like componentDidMount as in, it only runs once. Giving it no second argument acts as both componentDidMount and componentDidUpdate, as in it runs first on mount and then on every re-render. Giving it an array as second argument with any value inside, eg , … Read more
How to make a rest post call from ReactJS code?
Straight from the React Native docs: fetch(‘https://mywebsite.example/endpoint/’, { method: ‘POST’, headers: { ‘Accept’: ‘application/json’, ‘Content-Type’: ‘application/json’, }, body: JSON.stringify({ firstParam: ‘yourValue’, secondParam: ‘yourOtherValue’, }) }) (This is posting JSON, but you could also do, for example, multipart-form.) Also see docs for ReactJS AJAX FAQs if not using React Native.
What is the meaning of {…this.props} in Reactjs
It’s called spread attributes and its aim is to make the passing of props easier. Let us imagine that you have a component that accepts N number of properties. Passing these down can be tedious and unwieldy if the number grows. <Component x={} y={} z={} /> Thus instead you do this, wrap them up in … Read more
What is public/manifest.json file in create-react-app?
It’s a Web App Manifest that describes your application and it’s used by e.g. mobile phones if a shortcut is added to the homescreen. From MDN (linked above): The web app manifest provides information about an application (such as name, author, icon, and description) in a JSON text file. The purpose of the manifest is … Read more
ReactJS and Typescript : refers to a value, but is being used as a type here (TS2749)
Make sure you’re on a .tsx file and not a .ts file
Line 0: Parsing error: Cannot read property ‘map’ of undefined
Edit: as noted by Meng-Yuan Huang, this issue no longer occurs in react-scripts@^4.0.1 This error occurs because react-scripts has a direct dependency on the 2.xx range of @typescript-eslint/parser and @typescript-eslint/eslint-plugin. You can fix this by adding a resolutions field to your package.json as follows: “resolutions”: { “**/@typescript-eslint/eslint-plugin”: “^4.1.1”, “**/@typescript-eslint/parser”: “^4.1.1” } NPM users: add the … Read more
Dynamically import images from a directory using webpack
I feel like there must be some way to dynamically import all files from a specific directory as their name sans extension, and then use those files as needed. Not in ES6. The whole point of import and export is that dependencies can be determined statically, i.e. without executing code. But since you are using … Read more
React Child Component Not Updating After Parent State Change
There are two issues with your code. Your child component’s initial state is set from props. this.state = { data: props.data }; Quoting from this SO Answer: Passing the intial state to a component as a prop is an anti-pattern because the getInitialState (in our case the constuctor) method is only called the first time … Read more
react evironment variables .env return undefined
Three things to note here the variable should be prefixed with REACT_APP_ eg: REACT_APP_WEBSITE_NAME=hello You need to restart the server to reflect the changes. Make sure you have the .env file in your root folder(same place where you have your package.json) and NOT in your src folder. After that you can access the variable like … Read more