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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 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 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....

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....

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'`....

To set inline styles in React: Set the style property on an element to an object. Set specific CSS properties and values ​​to style the element. For example, ....

Use type guards to resolve the "Object is possibly null" error for the useRef hook in React, such as `if(inputRef.current){}`. Once null is excluded from the type of ref, we can access properties on the ref that correspond to its type....