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Styling — is one of the elements of the front-end triada that every web developer must know: HTML/CSS/JS. On the other hand, there is a large group of web developers who don’t like CSS. They prefer to use some helpers and libraries and basically t...

To fix the React.js warning "Invalid DOM property for. Did you mean htmlFor", use the `htmlFor` attribute instead of `for` on the tag. The `htmlFor` attribute is used because `for` is a reserved word in JavaScript....

When we don’t type the properties of a function or class component or forget to install typing for React, React.js will give an error “Parameter 'props' implicitly has an 'any' type”. To fix the error, explicitly set the type of the `props` obje...

When we call the map() method on a value that is not an array, we get a "TypeError: map is not a function" error. To fix this error, we need to console.log the value we are calling the map() method on and make sure we only call it on valid arrays....

React `ref` most commonly returns **undefined** or **null** when we try to access its current properties before its corresponding DOM element is rendered. To solve this problem, you need to access `ref` in the `useEffect` hook or when triggering an ev...

When we have 2 router components in the same React application, we will get the error “You cannot render a ` ` inside another ` `“. To fix this error, you need to make sure you use the router in your index.js file and do not use...

Make optionals with default values ​​in React TypeScript: Use a question mark to mark properties on a type as optional. Provide default values ​​for properties when destructuring them in the function's definition....

React.js "Uncaught TypeError: X is not a function" occurs when we try to call a function on a value that is not a function, such as calling the props object instead of a function. To fix this error, use console.log to print the value being called....

The "Cannot read property 'props' of undefined" error occurs when a class method is called without binding the correct context to the this keyword. To resolve this error, define the class method as an arrow function or use the bind method in the class...

When we don't set the to prop on the Link component of React router, we will get the error "Cannot read property 'pathname' of undefined". To fix the error, you need to set the `to` property on the link to a specific path, such as `Home...

Fix “Component definition is missing display name” errors by setting the displayName property on the component, for example `App.displayName = 'MyApp';` ....

React.js error "X is not defined react/jsx-no-undef" occurs when we forget to import a function, class, or variable in our code before using it. To fix this error, you need to make sure you import the value before using it in your code, e.g. import {m...

When we use the useEffect hook in our code but forget to import it, it will generate “Uncaught ReferenceError: useEffect is not defined”. To fix the error, you need to import the hook before using it - `import {useEffect} from 'react'`....

When we try to export an anonymous function using default export, it results in the warning “Unexpected default export of anonymous function.” To fix this error, you need to give the function a name before exporting it....

The React.js error “Property does not exist on type 'Readonly'” occurs when we try to access the props or state of an untyped class component. To fix the error, you need to use generics on the React.Component class to type the props or state of th...