Learn about JSX and how to use methods like the map function to loop inside React JSX and render a list of items.

Teams. Inspect the code and notice how all the elements are displayed in a single list item.
This code displays a bullet list of numbers between 1 and 5. This is a great default if your collection will not later reorder and an ergonomic improvement over your trained muscle memory of adding key={i} to every list.map() return value..

So to begin with, our shopping cart will look something like this.But after a few items have been added, it may look something like this:Now on our shopping cart page, we will want to output these items so that the user can see what they have ordered. Otherwise, it is ok to use an index for the If for any reason you want to experiment, then you can even use recursion to render a list. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Basic Example; Loop with Index; Multidimensional Array; Basic Example. {id: 35, item: 'jumper', color: 'red', size: 'medium', price: 20},{id: 42, item: 'shirt', color: 'blue', size: 'medium', price: 15},{id: 71, item: 'socks', color: 'black', size: 'all', price: 5}, Learn about JSX and how to use methods like the map function to loop inside React JSX and render a list of items. If you start using React-Hooks, and your component might need a life cycle method at some point. So if you wanted to loop through an array of child components, but preferred the first method we showed you, then you can! Let’s see a few examples: Table of Contents. I need to be able to loop over a number and return some jsx. Now there are some differences between for loop, forEach and map, but we won’t go into them here. See Wondering how to create loops in React? You need to use recursive iterators such as map, forEach, filter etc. Now go use this newfound knowledge to make some amazing web applications! A “key” is a special string attribute you need to include when creating lists of elements. Published Nov 06, 2018. However, if you check the console log, you will see that there is a warning like, “Warning: Each child in a list should have a unique Thanks to adding keys there are no more warnings in the console. Using an index as a key in certain situations could lead us into a pitfall and cause bugs. I hope that after reading this article you are now more confident with React and know how to use loops in JSX.Thomas Findlay is a web and mobile developer, mentor, technical writer and consultant with almost six years of experience. But what if we want to loop through data to output lots of child components? The first is item which simply corresponds to a single item inside of our Let’s just take a quick look at how this chunk of code in full:Then later on in our code, when we want to use it, we simply create an outer And just like that, our page will render each item in our shopping cart as a unique The second way that we could have handled this is very similar, and may feel a little more familiar.Instead of putting our this.item block of code inside of the class constructor, we could have simply put it at the top of ourThis allows us to use the more traditional const syntax (or var or let if you prefer).If we do this, it also means that we can write this instead:Now some people will argue that you shouldn’t pollute the Okay, so we know how to render lists using loops. If you are unsure about how to use map functions, I recommend that you take a moment to read this article about using Let us imagine that we are building an eCommerce website where we sell clothes. And, that is when you start using useEffect() (a.k.a … The React docs strongly encourage the use of the map function, not just for its simplicity, but because it creates a new array from the data, rather than trying to mutate/overwrite existing data.This second point is vital. Usually you would render lists inside a component.. We can refactor the previous example into a component that accepts an array of numbers and outputs a list of elements. If you need the same value in your component, pass it explicitly as a prop with a different name:Sometimes this results in clearer code, but this style can also be abused. However, there is more you need to know. However, I would not recommend doing that and, in most cases, you should really stick with the As you can see there are quite a few different ways in which you can render a list of items in React. Consider we have an array of users, we need to loop them using for loop and render the elements into the dom. getElementsByTagName() returns a NodeList, which can be used similar to an array, i.e., with bracket notation.Each element in the NodeList will represent a <ul> element.. Thomas has designed and developed websites and mobile applications for individuals and small and large businesses. How to loop in a React component JSX. JSX is a custom syntax extension to JavaScript which is used for creating markup with React. By clicking “Post Your Answer”, you agree to our To subscribe to this RSS feed, copy and paste this URL into your RSS reader. React Loops work alongside React Hooks as part of the novel React Velcro architecture for building sticky, … If it is not available, then create one for each item before the list is rendered. The following example shows what happens when simply rendering a list in React without any processing. Let’s see two very similar ways that we can handle this.Inside of our App class constructor, we will create this.items and assign it to We pass our map function two parameters. Like in JavaScript, it is up to you to decide whether it is worth extracting a variable for readability. In this tutorial, we are going to learn about how to loop through array of elements in a react. The most common way of doing that is with the You should see a rendered list. In this article, we’re going to see how to Iterate with foreach loop. React gives you a finer level of control that makes using it more easier to understand. At the end of the day, it’s all regular JavaScript!So there you have it, we have shown you three powerful ways to loop through arrays using the latest JavaScript techniques in React.