How to disable button in React.js

Using refs is not best practice because it reads the DOM directly, it’s better to use React’s state instead. Also, your button doesn’t change because the component is not re-rendered and stays in its initial state. You can use setState together with an onChange event listener to render the component again every time the input field changes: Here’s a working example:

Show or hide element in React

React circa 2020 In the onClick callback, call the state hook’s setter function to update the state and re-render:  Run code snippetExpand snippet JSFiddle React circa 2014 The key is to update the state of the component in the click handler using setState. When the state changes get applied, the render method gets called again with the new state:

What do these three dots in React do?

That’s property spread notation. It was added in ES2018 (spread for arrays/iterables was earlier, ES2015), but it’s been supported in React projects for a long time via transpilation (as “JSX spread attributes” even though you could do it elsewhere, too, not just attributes). {…this.props} spreads out the “own” enumerable properties in props as discrete properties … Read more

ReactJs CreateClass is not a function

Per the documents, you need to get the npm create react class package. From the command line of your project’s file path, you need to do npm install create-react-class –save, and then modify the code like this: You also need React DOM to render the components like this: