Altcademy - a Forbes magazine logo Best Coding Bootcamp 2023

How to use arrays in ReactJS

Understanding Arrays in ReactJS

If you're new to programming, you may find the concept of arrays a bit confusing, but don't worry. I'll explain it in a simple way. Think of arrays as a kind of shopping list. You have a list of items you want to buy, and you can add items, remove items, or change items on the list. In programming, arrays are just like that shopping list. They are used to store multiple values in a single variable.

Creating Arrays in ReactJS

Creating an array in ReactJS is just as easy as creating a shopping list. Here's an example:

let shoppingList = ['Apples', 'Oranges', 'Bananas'];

In this example, 'Apples', 'Oranges', and 'Bananas' are the items in our shopping list, or in other words, the elements of our array. Each element in an array is assigned a unique index, starting from 0. So, 'Apples' is at index 0, 'Oranges' is at index 1, and 'Bananas' is at index 2.

Accessing Array Elements

Accessing elements in an array is like picking an item from your shopping list. You just need to know its position or index. Here's how you can do it:

console.log(shoppingList[0]);  // Outputs: Apples

In this example, we're accessing the element at index 0 of the shoppingList array, which is 'Apples'.

Modifying Array Elements

If you want to change an item on your shopping list, you can do so by assigning a new value to a specific index. Here's how:

shoppingList[1] = 'Pears';  // Changes 'Oranges' to 'Pears'

Now, if you print out your shopping list, you'll see that 'Oranges' has been replaced with 'Pears'.

Adding Elements to Array

Adding an item to your shopping list is as simple as using the push() method in JavaScript. This method allows you to add new elements to the end of an array.

shoppingList.push('Strawberries');  // Adds 'Strawberries' to the end of the array

Now, the shoppingList array looks like this: ['Apples', 'Pears', 'Bananas', 'Strawberries'].

Removing Elements from Array

Removing an item from your shopping list can be done using the pop() method in JavaScript. This method removes the last element of an array.

shoppingList.pop();  // Removes 'Strawberries' from the array

Now, the shoppingList array looks like this: ['Apples', 'Pears', 'Bananas'].

Rendering Arrays in ReactJS

In ReactJS, we often need to display lists of data. We can use arrays and the map() method for this purpose. The map() method creates a new array by performing a function on each element in the original array.

Here's an example of how you can display a list of data in ReactJS:

function ShoppingList() {
  const shoppingList = ['Apples', 'Pears', 'Bananas'];

  return (
      {, index) => (
        <li key={index}>{item}</li>

In this example, we're creating an unordered list (<ul>) and using the map() method to create a list item (<li>) for each element in the shoppingList array. Notice how we're using a unique key for each list item. This is a requirement in ReactJS when creating lists of elements.


So, there you have it! We've just taken a stroll through the supermarket of ReactJS, exploring the concept of arrays. Just as a shopping list helps us remember and manage the items we need, arrays in ReactJS help us store and manipulate data efficiently. Remember that practice is key when learning new concepts in programming. So, why not create your own shopping list and play around with adding, removing, or modifying items? Happy coding!