ReactJS

How to Integrate Mailchimp Forms in a React Project

Published Jul 5, 2023

Updated Jul 5, 2023

3 min read

This article was written over 18 months ago and may contain information that is out of date. Some content may be relevant but please refer to the relevant official documentation or available resources for the latest information.

Intro

Today we will cover how to set up an email signup form using React and Mailchimp. This blog will be using the starter.dev cra-rxjs-styled-components template to expedite the process. This article assumes you have a basic understanding of React, and have set up a Mailchimp account. Here is the code repo if you want to review it while reading, or just skip ahead. We will start with setting up our React project using Starter.dev for simplicity, and then finish it up by integrating the two for our signup form.

To start, we will be using the command yarn create @this-dot/starter --kit cra-rxjs-styled-components, which can be found here. We’ll go ahead, and give the project a name. I will be calling mine react-mailchimp.

Now we will navigate into the project and do a yarn install. Then we can run yarn run dev to get it up and running locally on localhost:3000. This should have us load up on the React App, RxJS, and styled-components Starter kit page.

With that all set, we’ll also need to install jsonp by using yarn add jsonp. We’ll be using jsonp instead of fetch to avoid any CORS issues we may run into. This also makes for an easy and quick process by not relying on their API, which can’t be utilized by the client.

Now that we have our project set up, we will go ahead and go and grab our form action URL from MailChimp. This can be found by going to your Audience > Signup Forms > Embedded Forms > Continue and then grabbing the form action URL found in the Embedded Form Code. We need to make a small change to the URL and swap /post? with /post-json?.

We can now start setting up our form input, and our submit function. I will add a simple form input and follow it up, and a submit function. Inside the submit function, we will use our imported jsonp to invoke our action URL.

import { useState } from 'react';
import jsonp from 'jsonp';

export const MailChimp = () => {
 const [email, setEmail] = useState('');

 const onSubmit = (e: any) => {
   e.preventDefault();
   const url = 'insert-mailchimp-action-url-here';
   jsonp(`${url}&EMAIL=${email}`, { param: 'c' }, (_: any, data: any) => {
     console.log('data', data);
     const { msg } = data;

     alert(msg);
   });
 };

 return (
   <div>
     <form onSubmit={onSubmit}>
       <label>Email</label>
       <input
         type="email"
         name="EMAIL"
         required
         onChange={(e) => setEmail(e.target.value)}
       ></input>
       <button type="submit">Submit</button>
     </form>
   </div>
 );
};

We’ll also add a quick alert to let the user know that it was successful and that’s it! We’ve now successfully added the email to our MailChimp account.

Conclusion

Today, we covered how to integrate Mailchimp with a react app using the cra-rxjs-styled-components template from starter.dev. I highly recommend using starter.dev to get your project up and running quickly. Here is the code repo again for you to check out.

This Dot is a consultancy dedicated to guiding companies through their modernization and digital transformation journeys. Specializing in replatforming, modernizing, and launching new initiatives, we stand out by taking true ownership of your engineering projects.

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About the author(s)

William Hutt
I'm a software engineer with an interest in web development.
@willHutt

Communication Between Client Components in Next.js

Communication Between Client Components in Next.js In recent years, Next.js has become one of the most popular React frameworks for building server-rendered applications. With the introduction of the App Router in Next.js 13, the framework has taken a major leap forward by embracing a new approach to building web applications: the concept of server components and client components. This separation of concerns allows developers to strategically decide which parts of their application should be rendered on the server and which are then hydrated in the browser for interactivity. The Challenge: Communicating Between Client Components While server components offer numerous benefits, they also introduce a new challenge: how can client components within different boundaries communicate with each other? For instance, let's consider a scenario where you have a button (a client component) and a separate client component that displays the number of times the button has been clicked. In a regular React application, this would typically be accomplished by lifting the state to a common ancestor component, allowing the button to update the state, which is then passed down to the counter display component. However, the traditional approach may not be as straightforward in a Next.js application that heavily relies on server components, with client components scattered across the page. This blog post will explore three ways to facilitate communication between client components in Next.js, depending on where you want to store the state. Lifting State to a Common Client Component One approach to communicating between client components is to lift the state to a common client component. This could be a React context provider, a state management system like Zustand, or any other solution that allows you to share state across components. The key aspect is that this wrapper component should be higher up in the tree (perhaps even in the layout) and accept server components as children. Next.js allows you to interleave client and server components as much as you want, as long as server components are passed to client components as props or as component children. Here's how this approach might look in practice. First of all, we'd create a wrapper client component that holds the state: ` This wrapper component can be included in the layout: ` Any server components can be rendered within the layout, potentially nesting them several levels deep. Finally, we'd create two client components, one for the button and one for the counter display: ` ` The entire client and server component tree is rendered on the server, and the client components are then hydrated in the browser and initialized. From then on, the communication between the client components works just like in any regular React application. Check out the page using this pattern in the embedded Stackblitz window below: Using Query Params for State Management Another approach is to use query params instead of a wrapper client component and store the state in the URL. In this scenario, you have two client components: the button and the counter display. The counter value (the state) is stored in a query param, such as counterValue. The client components can read the current counter value using the useSearchParams hook. Once read, the useRouter hook can update the query param, effectively updating the counter value. However, there's one gotcha to this approach. If a route is statically rendered, calling useSearchParams will cause the client component tree up to the closest Suspense boundary to be client-side rendered. Next.js recommends wrapping the client component that uses useSearchParams in a boundary. Here's an example of how this approach might look. The button reads the current counter value and updates it on click by using the router's replace function: ` The counter display component is relatively simple, only reading the counter value: ` And here is the page that is a server component, hosting both of the above client components: ` Feel free to check out the above page in the embedded Stackblitz below: Storing State on the Server The third approach is to store the state on the server. In this case, the counter display component accepts the counter value as a prop, where the counter value is passed by a parent server component that reads the counter value from the database. The button component, when clicked, calls a server action that updates the counter value and calls revalidatePath() so that the counter value is refreshed, and consequently, the counter display component is re-rendered. It's worth noting that in this approach, unless you need some interactivity in the counter display component, it doesn't need to be a client component – it can be purely server-rendered. However, if both components need to be client components, here's an example of how this approach might look. First, we'll implement a server action that updates the counter value. We won't get into the mechanics of updating it, which in a real app would require a call to the database or an external API - so we're only commenting that part. After that, we revalidate the path so that the Next.js caches are purged, and the counter value is retrieved again in server components that read it. ` The button is a simple client component that calls the above server action when clicked. ` The counter display component reads the counter value from the parent: ` While the parent is a server component that reads the counter value from the database or an external API. ` This pattern can be seen in the embedded Stackblitz below: Conclusion Next.js is a powerful framework that offers various choices for implementing communication patterns between client components. Whether you lift state to a common client component, use query params for state management, or store the state on the server, Next.js provides all the tools you need to add a communication path between two separate client component boundaries. We hope this blog post has been useful in demonstrating how to facilitate communication between client components in Next.js. Check out other Next.js blog posts we've written for more insights and best practices. You can also view the entire codebase for the above snippets on StackBlitz....

Jun 21, 2024

5 mins

NextJSReact

Why is My React Reducer Called Twice and What the Heck is a Pure Function?

Why is My React Reducer Called Twice and What the Heck is a Pure Function? In a recent project, we encountered an interesting issue: our React reducer was dispatching twice, producing incorrect values, such as incrementing a number in increments of two. We hopped on a pairing session and started debugging. Eventually, we got to the root of the problem and learned the importance of pure functions in functional programming. This article will explain why our reducer was being dispatched twice, what pure functions are, and how React's strict mode helped us identify a bug in our code. The Issue We noticed that our useReducer hook was causing the reducer function to be called twice for every action dispatched. Initially, we were confused about this behavior and thought it might be a bug in React. Additionally, we had one of the dispatches inside a useEffect, which caused it to be called twice due to React strict mode, effectively firing the reducer four times and further complicating our debugging process. However, we knew that React's strict mode caused useEffect to be called twice, so it didn't take very long to realize that the issue was not with React but with how we had implemented our reducer function. React Strict Mode React's strict mode is a tool for highlighting potential problems in an application. It intentionally double-invokes specific lifecycle methods and hooks (like useReducer and useEffect) to help developers identify side effects. This behavior exposed our issue, as we had reducers that were not pure functions. What is a Pure Function? A pure function is a function that: - Is deterministic: Given the same input, always returns the same output. - Does Not Have Side Effects: Does not alter any external state or have observable interactions with the outside world. In the context of a reducer, this means the function should not: - Modify its arguments - Perform any I/O operations (like network requests or logging) - Generate random numbers - Depend on any external state Pure functions are predictable and testable. They help prevent bugs and make code easier to reason about. In the context of React, pure functions are essential for reducers because they ensure that the state transitions are predictable and consistent. The Root Cause: Impure Reducers Our reducers were not pure functions. They were altering external state and had side effects, which caused inconsistent behavior when React's strict mode double-invoked them. This led to unexpected results and made debugging more difficult. The Solution: Make Reducers Pure To resolve this issue, we refactored our reducers to ensure they were pure functions. Here's an extended example of how we transformed an impure reducer into a pure one in a more complex scenario involving a task management application. Let's start with the initial state and action types: ` And here's the impure reducer similar to what we had initially: ` This reducer is impure because it directly modifies the state object, which is a side effect. To make it pure, we must create a new state object for every action and return it without modifying the original state. Here's the refactored pure reducer: ` Key Changes: - Direct State Modification: In the impure reducer, the state is directly modified (e.g., state.tasks.push(action.payload)). This causes side effects and violates the principles of pure functions. - Side Effects: The impure reducer included side effects such as logging and direct state changes. The pure reducer eliminates these side effects, ensuring consistent and predictable behavior. I've created an interactive example to demonstrate the difference between impure and pure reducers in a React application. Despite the RESET_TASKS action being implemented similarly in both reducers, you'll notice that the impure reducer does not reset the tasks correctly. This problem happens because the impure reducer directly modifies the state, leading to unexpected behavior. Check out the embedded StackBlitz example below: Conclusion Our experience with the reducer dispatching twice was a valuable lesson in the importance of pure functions in React. Thanks to React's strict mode, we identified and fixed impure reducers, leading to more predictable and maintainable code. If you encounter similar issues, ensure your reducers are pure functions and leverage React strict mode to catch potential problems early in development. By embracing functional programming principles, you can write cleaner, more reliable code that is easier to debug and maintain....

Jun 14, 2024

3 mins

React

Setting Up a Shopify App: Updating Customer Orders with Tracking Info

Today, we are wrapping up our adventure! Last time we learned about retrieving fulfillment IDs, but this time, we encounter the final boss: updating customer orders with tracking information. Now, if we have any new adventurers with us, I recommend heading over here to prep yourself for the encounter ahead. If you just need a recap of our last session, you can head over here. Alternatively, if you just want the code from last time that can be found here. If you want to skip ahead and look at the code it can be found here. With that all said we’re off to battle with updating customer orders with tracking information! Body We’re gonna start by heading over to our app/routes/app.index.jsx file, and grabbing the code found in the loader function. We’ll be moving that to our action function so we can add our post call. We’ll completely replace the existing action function code, and because of that, we need to make a couple of tweaks to the code base. We’re going to remove anything that has a reference to actionData?.product or productId. Now what we need to add the call admin.rest.resources.Fulfillment, which will allow us to update customer orders with tracking information. We’ll be placing it under our fulfillment ID loop. Here is a general example of what that call will look like. ` This is a good start as we now have our fulfillment information and get to add a few things to it. We’ll start off by adding our fulfillment ID and then our fulfillment tracking info. ` Awesome! Now we have given the fulfillment ID and tracking info we need to the fulfillment object, but we need to do one more thing for that to update. Thankfully, it’s a small thing and that’s to save it. ` Now, the above will work wonderfully for a single order, but based on our prior adventurers, we had multiple ids for orders that needed to be completed. So our next step is to loop over our fulfillment object. Though before we do that, here is what the current code should look like: ` Before we go to loop over this, we’re going to add a small change to fulfillmentIds. We’re going to create a new variable and add the company and tracking number information. So above the fulfillment variable, we will add this: ` Perfect! Now for the looping, we’ll just wrap it in a for of loop: ` Now that the loop is set up, we will be able to go through all of the orders and update them with the shipping company and a tracking number. So we’ll run a yarn dev, and navigate to the app page by pressing the p button. We should see our template page, and be able to click on the Generate a product button. Now we’ll navigate to our order page and we should see all open orders set to fulfilled. Conclusion Here we are. At the end of our three part saga, we covered a fair share of things in order to get our customer orders tracking information added, and can now take a long rest to rejuvenate....

Aug 28, 2023

3 mins

Shopify

“Music and code have a lot in common,” freeCodeCamp’s Jessica Wilkins on what the tech community is doing right to onboard new software engineers

Before she was a software developer at freeCodeCamp, Jessica Wilkins was a classically trained clarinetist performing across the country. Her days were filled with rehearsals, concerts, and teaching, and she hadn’t considered a tech career until the world changed in 2020. > “When the pandemic hit, most of my gigs were canceled,” she says. “I suddenly had time on my hands and an idea for a site I wanted to build.” That site, a tribute to Black musicians in classical and jazz music, turned into much more than a personal project. It opened the door to a whole new career where her creative instincts and curiosity could thrive just as much as they had in music. Now at freeCodeCamp, Jessica maintains and develops the very JavaScript curriculum that has helped her and millions of developers around the world. We spoke with Jessica about her advice for JavaScript learners, why musicians make great developers, and how inclusive communities are helping more women thrive in tech. Jessica’s Top 3 JavaScript Skill Picks for 2025 If you ask Jessica what it takes to succeed as a JavaScript developer in 2025, she won’t point you straight to the newest library or trend. Instead, she lists three skills that sound simple, but take real time to build: > “Learning how to ask questions and research when you get stuck. Learning how to read error messages. And having a strong foundation in the fundamentals” She says those skills don’t come from shortcuts or shiny tools. They come from building. > “Start with small projects and keep building,” she says. “Books like You Don’t Know JS help you understand the theory, but experience comes from writing and shipping code. You learn a lot by doing.” And don’t forget the people around you. > “Meetups and conferences are amazing,” she adds. “You’ll pick up things faster, get feedback, and make friends who are learning alongside you.” Why So Many Musicians End Up in Tech A musical past like Jessica’s isn’t unheard of in the JavaScript industry. In fact, she’s noticed a surprising number of musicians making the leap into software. > “I think it’s because music and code have a lot in common,” she says. “They both require creativity, pattern recognition, problem-solving… and you can really get into flow when you’re deep in either one.” That crossover between artistry and logic feels like home to people who’ve lived in both worlds. What the Tech Community Is Getting Right Jessica has seen both the challenges and the wins when it comes to supporting women in tech. > “There’s still a lot of toxicity in some corners,” she says. “But the communities that are doing it right—like Women Who Code, Women in Tech, and Virtual Coffee—create safe, supportive spaces to grow and share experiences.” She believes those spaces aren’t just helpful, but they’re essential. > “Having a network makes a huge difference, especially early in your career.” What’s Next for Jessica Wilkins? With a catalog of published articles, open-source projects under her belt, and a growing audience of devs following her journey, Jessica is just getting started. She’s still writing. Still mentoring. Still building. And still proving that creativity doesn’t stop at the orchestra pit—it just finds a new stage. Follow Jessica Wilkins on X and Linkedin to keep up with her work in tech, her musical roots, and whatever she’s building next. Sticker illustration by Jacob Ashley....

Apr 25, 2025

3 mins

JavaScriptSoftware Engineering

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How to Integrate Mailchimp Forms in a React Project

Intro

Conclusion

William Hutt

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