React.memo usage - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to wrap the component with React.memo.

React

const MemoizedComponent = [1](MyComponent);

Drag options to blanks, or click blank then click option'

AReact.useEffect

BReact.memo

CReact.useState

DReact.createContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using React.useState or React.useEffect instead of React.memo

Trying to call React.memo without parentheses

React.memo is used to wrap a component to memoize it and avoid unnecessary re-renders.

2fill in blank

medium

Complete the code to export the memoized component as default.

React

export default [1](MyComponent);

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AReact.memo

BReact.useCallback

CReact.forwardRef

DReact.lazy

Attempts:

3 left

💡 Hint

Common Mistakes

Using React.useCallback which memoizes functions, not components

Using React.forwardRef which is for refs, not memoization

Exporting the component wrapped in React.memo ensures it is memoized when imported elsewhere.

3fill in blank

hard

Fix the error in the code to correctly memoize the component.

React

const MyComponent = (props) => { return <div>{props.text}</div>; };
const MemoComp = React.[1](MyComponent);

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Amemo

BuseMemo

Cmemorize

Dmemoize

Attempts:

3 left

💡 Hint

Common Mistakes

Using misspelled versions like memoize or memorize

Confusing React.memo with React.useMemo

The correct React API is React.memo. Other options are invalid or different hooks.

4fill in blank

hard

Fill both blanks to create a memoized component with a custom comparison function.

React

const MemoComp = React.memo(MyComponent, [1]);

function [2](prevProps, nextProps) {
  return prevProps.value === nextProps.value;
}

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AareEqual

BcompareProps

CarePropsEqual

DcheckProps

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the function and the argument

Passing a non-function value as the second argument

The custom comparison function is passed as the second argument to React.memo. Naming it areEqual is common and matches usage.

5fill in blank

hard

Fill all three blanks to memoize a component and export it with a custom comparison function.

React

function [1](prev, next) {
  return prev.count === next.count;
}

const MemoComp = React.[2](Counter, [3]);

export default MemoComp;

Drag options to blanks, or click blank then click option'

AareEqual

Bmemo

DuseMemo

Attempts:

3 left

💡 Hint

Common Mistakes

Using useMemo instead of memo

Mismatching function names between declaration and argument

The function areEqual is the custom comparison passed to React.memo to memoize the component with custom logic.