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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...

Use wildcard placeholders to handle 404 pages not found in React routers, such as ` } />` . A route with an asterisk `*` acts as a catch-all route. It matches only when no other routes match....

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....

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....

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...

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 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....

When we try to return an array of elements from a function component, a React.js error “Type '() => JSX.Element[]' is not assignable to type FunctionComponent” occurs. To fix this error, you need to wrap the array of elements in a React fragment....

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...

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 try to pass an element or React component as a parameter to another component but the input parameter is incorrect, the error "JSX element type does not have any construct or call signatures" will appear. To solve this error, you need to use `...

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...

Type onKeyUp events in React using React.KeyboardEvent type. KeyboardEvent interface is used for onKeyUp events. We can access the value of the key pressed by the user through `event.key`....

In React, when we initialize a ref with a null value and do not include null in its type, an error "Cannot assign to 'current' because it is a read-only property" will occur. To fix the error, include null in the type of ref, such as `...

The 'react-hooks/exhaustive-deps' rule warns us when we are missing dependencies in effect hooks. To get rid of the warning, move the function or variable declaration inside the `useEffect` hook, remember arrays and objects that change on every render...