vinaypal_Frontend

[Vianypal]

Q-1.) Explain what the simple List component does. ans.The provided code displays a list of things with selectable options using the React component "List" in React. The "WrappedSingleListItem" and "WrappedListComponent" sub-components make up this component. A single item in the list is represented by the "WrappedSingleListItem" component, a memoized functional component. It requires the following four arguments: "text," "onClickHandler," "isSelected," and "index," and it generates a list item element with a background color based on the selection status. Another memoized functional component called "WrappedListComponent" uses "WrappedSingleListItem" to create a list of things.The "items" argument accepts an array of objects with the "text" and "key" attributes. The component keeps track of the index of the currently selected item using the "useState" and "useEffect" hooks. The SingleListItem component for each item is produced by the List component after iterating through an array of objects. The SingleListItem component receives the pertinent props to handle the presentation and behaviour of each item. The useState hook, which is managed by the List component, also enables it to keep track of the presently selected item in the list by managing the state of the selected index. The handleClick function manages user clicks and modifies the selected index in response to user input. The List component offers a dynamic and interactive interface in this way.

Q-2) : What problems/warnings are there with the code?

ans . error 1 . In the SingleListItem component, the isSelected prop is expected to be a boolean, but it is being passed the selectedIndex state, which is a number. This could cause unexpected behavior if selectedIndex is not converted to a boolean value.

   Error 2 . In the SingleListItem component, the onClickHandler prop is expected to be a function, but it is being passed a function call with an argument (onClick={onClickHandler(index)}). This will cause the function to be called immediately instead of when the element is clicked.

Error 3 .In the ListComponent component, the items prop is not properly validated using PropTypes. The array type should be lowercase (PropTypes.arrayOf) and the shape definition should use PropTypes.shape instead of PropTypes.shapeOf.

Error 4. In the ListComponent component, the selectedIndex state is being set to null in the useEffect hook, but it should be initialized to a default value of -1 to match the expected prop type of isSelected in the SingleListItem component.

-3) Please fix, optimize, and/or modify the component as much as you think is necessary. ans . import React, { useState, useEffect, memo } from 'react'; import PropTypes from 'prop-types';

// Single List Item const WrappedSingleListItem = ({ index, isSelected, onClickHandler, text, }) => { return ( <li style={{ backgroundColor: ${isSelected ? 'green' : 'red'} }} onClick={() => onClickHandler(index)}

{text} ); };

WrappedSingleListItem.propTypes = { index: PropTypes.number, isSelected: PropTypes.bool, onClickHandler: PropTypes.func.isRequired, text: PropTypes.string.isRequired, };

const SingleListItem = memo(WrappedSingleListItem);

// List Component const WrappedListComponent = ({ items, }) => { const [selectedIndex, setSelectedIndex] = useState(null);

useEffect(() => { setSelectedIndex(null); }, [items]);

const handleClick = index => { setSelectedIndex(index); };

return ( <ul style={{ textAlign: 'left' }}> {items.map((item, index) => ( <SingleListItem onClickHandler={() => handleClick(index)} text={item.text} index={index} isSelected={selectedIndex === index} /> ))} ) };

WrappedListComponent.propTypes = { items: PropTypes.arrayOf(PropTypes.shape({ text: PropTypes.string.isRequired, })), };

WrappedListComponent.defaultProps = { items: null, };

const List = memo(WrappedListComponent);

export default List;