How fix this warrning warning Array.prototype.map() expects a return value from arrow function array-callback-return?

Question

My real problem is : i have data.js file inside this file i create a static array like this:

 const products =
    [
        {
            _id:1,
            name: 'Slim Shirt',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4.5,
            numReviews:10
        },
        {
            _id:2,
            name: 'First Shirt',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 50,
            rating: 4.5,
            numReviews:10
        },
        {
            _id:3,            
            name: 'Best Pant',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4,
            numReviews:5
        },
        {
            _id:4,            
            name: 'Slim Shirt',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4.2,
            numReviews:7
        },
        {
            _id:5,            
            name: 'Slim Shirt',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4.5,
            numReviews:10
        },
        {
            _id:6,            
            name: 'Slim Pant',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4.5,
            numReviews:10
        },
        {
            _id:7,            
            name: 'Slim Shirt',
            category:'Shirt',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4.5,
            numReviews:10
        },
        {
            _id:8,            
            name: 'Slim Shirt',
            category:'Pant',
            image:'/images/d1.jpg',
            price: 60,
            rating: 4.5,
            numReviews:10
        },
    ];


    export default products;

And i have other react component HomeScreen.js and i import my array and use it like this,

import React from 'react';
import { Link } from 'react-router-dom';
import  Products  from './../data';

function HomeScreen(props){
    console.log(Products)
    return (<ul className="products">
                {Products.map(product =>{
                    <li>
                    <div className="product">
                        <img className="product-image" src={product.image} alt="product"/>
                        <div className="product-name">
                            <Link to={'/product' + product._id}>{product.name}</Link>
                        </div>
                        <div className="product-brand">{product.brand}</div>
                        <div className="product-price">{product.price}</div>
                        <div className="product-rating">{product.rating}</div>
                    </div>
                </li>
                })}                    
                </ul>)
}
export default HomeScreen;

But, I style have this warning

warning Array.prototype.map() expects a return value from arrow function  array-callback-return

Thanks to help me guys.

Answer 1

Map function returns an array with the results of calling a function for every array element, which means that the functions needs to return the mapped element.

In your case you can explicitly indicate a return statement as such:

{Products.map(product =>{
     return (
          <li>
                    <div className="product">
                        <img className="product-image" src={product.image} alt="product"/>
                        <div className="product-name">
                            <Link to={'/product' + product._id}>{product.name}</Link>
                        </div>
                        <div className="product-brand">{product.brand}</div>
                        <div className="product-price">{product.price}</div>
                        <div className="product-rating">{product.rating}</div>
                    </div>
        </li>
    )
                })}   

Or you can do it implicitly as such:

{Products.map(product => ( // Note that we're using parenthesis here rather than braces
                    <li>
                    <div className="product">
                        <img className="product-image" src={product.image} alt="product"/>
                        <div className="product-name">
                            <Link to={'/product' + product._id}>{product.name}</Link>
                        </div>
                        <div className="product-brand">{product.brand}</div>
                        <div className="product-price">{product.price}</div>
                        <div className="product-rating">{product.rating}</div>
                    </div>
                </li>
                ))}   

Answer 2

When you use {} in an arrow function it creates a code block that expects an explicit return statement

Just change the {} to () and an implicit return occurs

 {Products.map(product => (
         <li>....</li>
 ))}

Basic example:

 const arr = [1,2,3]; let res = arr.map(n => { return n*2}) console.log('explicit return', res) res = arr.map(n => (n*2)) console.log('implicit return', res)

Answer 3

To return a value with arrow functions you have 2 options:

1. () => 'value'
2. () => { return 'value' }

In your case you added an additional accolade so you need to specify the returned value with the key word return. But, I do recommend just returning the value directly:

  {Products.map(product => (<li>
                    <div className="product">
                        <img className="product-image" src={product.image} alt="product"/>
                        <div className="product-name">
                            <Link to={'/product' + product._id}>{product.name}</Link>
                        </div>
                        <div className="product-brand">{product.brand}</div>
                        <div className="product-price">{product.price}</div>
                        <div className="product-rating">{product.rating}</div>
                    </div>
                </li>)
                )}

Answer 4

Return the value from your map arrow function

                {Products.map(product =>{
                   return (
                    <li>
                    <div className="product">
                        <img className="product-image" src={product.image} alt="product"/>
                        <div className="product-name">
                            <Link to={'/product' + product._id}>{product.name}</Link>
                        </div>
                        <div className="product-brand">{product.brand}</div>
                        <div className="product-price">{product.price}</div>
                        <div className="product-rating">{product.rating}</div>
                    </div>
                </li>
)
                })}