Quick Answer:
To set up dynamic imports in JavaScript, you use the import() function, which returns a Promise. The real work isn’t the syntax—it’s deciding what to split. A solid setup for dynamic imports focuses on route-based or component-based splitting, which can reduce your initial bundle size by 40-60% and is supported in all modern browsers and build tools like Webpack and Vite.
You have a JavaScript bundle that’s getting fat. The page load is sluggish, and you know you need to split it up. The tutorials make it sound trivial: just wrap your import in a function. But if you’ve tried that, you know the real question isn’t how to write import(). It’s how to structure your entire application so that this setup for dynamic imports actually delivers the performance gains you were promised, without turning your code into a tangled mess of promises and loading states.
I have seen this exact scenario play out for two decades, from the early days of AMD modules with RequireJS to the modern ES2020 spec. The syntax is the easy part. The strategy is what separates a performant app from a fragmented one. Let’s talk about what a proper setup for dynamic imports actually entails when you’re building for real users in 2026.
Why Most Setup for Dynamic Imports Efforts Fail
Here is what most people get wrong: they think dynamic imports are about code splitting. They are not. They are about user experience splitting. The failure happens when developers treat it as a purely technical, build-step optimization. They run a tool, it creates 100 chunks, and they call it a day. The real issue is not bundle size. It’s predicting what the user needs next and having it ready just before they ask for it.
I have seen teams obsess over splitting every third-party library into its own chunk, creating a waterfall of network requests that actually makes the app slower. They’ll dynamically import a utility function that’s 2KB, not realizing the overhead of the request and promise resolution is greater than the payload. The common approach is to split where it’s easy, not where it’s impactful. You end up with a configuration that looks good in a bundle analyzer but feels worse in the browser.
The other major mistake is ignoring the loading state. Dynamic imports are asynchronous. Your UI can’t just freeze while you wait for the module. Most tutorials show you the happy path—the .then() block. They don’t show you the skeleton loader, the error boundary, or the fallback UI you need when the network is slow or the chunk fails to load. That’s not an edge case; it’s a core part of the setup.
A few years back, I was brought into a large e-commerce project that had “optimized” their React app. The initial load was fast, but clicking on the product filter would cause a noticeable 2-3 second hang. The team had dynamically imported the entire filter component module, which was massive because it included a charting library and a heavy utility set. They split the code, but they didn’t split the logic. The user tapped and got nothing—no spinner, no feedback. We fixed it by peeling the charting library into its own secondary chunk and adding an immediate UI skeleton. The lesson was clear: splitting at the wrong boundary creates a worse experience than no splitting at all.
What Actually Works: A Strategic Approach
Forget about tools for a minute. Your setup for dynamic imports must start with a map of your user’s journey. Where are the clear boundaries? In a typical web app, these are your routes. Each route is a prime candidate for a dynamic import. This is route-based splitting and it’s your first and most effective lever. Tools like React Router and Vue Router have built-in patterns for this. It works because it aligns with what the user is consciously asking for: a new page.
The Component-Level Decision
After routes, look at heavy components that are below the fold or behind user interactions. A modal with a rich text editor, a dashboard chart, an interactive map. These should load on demand. The trick is to use the dynamic import in conjunction with the browser’s own capabilities. Use the Intersection Observer API to load a component when it’s about to scroll into view. Use a click handler to preload the module for a modal right on mouseenter. This is where you move from naive splitting to intelligent preloading.
Handling the Promise Properly
This is the unsexy, crucial part. Wrapping a dynamic import in a React lazy() or Vue’s defineAsyncComponent is just the start. You must wrap that lazy component in a
Dynamic imports aren’t a performance feature. They’re a design feature. You’re designing how your application reveals itself to the user over time, piece by intentional piece.
— Abdul Vasi, Digital Strategist
Common Approach vs Better Approach
| Aspect | Common Approach | Better Approach |
|---|---|---|
| Splitting Strategy | Splitting every npm package or arbitrary function based on size alone. | Splitting at route boundaries first, then for heavy below-the-fold or interactive components. |
| Loading UI | No fallback, leading to frozen UI or layout shift when the chunk loads. | Using a structured skeleton fallback that preserves layout, inside an error boundary. |
| Tool Reliance | Fully dependent on Webpack’s magic comments and auto-split configuration. | Using tooling for bundling, but controlling the split points explicitly in application code. |
| Preloading | Either no preloading, or preloading everything, hurting bandwidth. | Strategic preloading on user intent (e.g., mouseenter on a button) or viewport proximity. |
| Testing | Only testing the happy path on a fast development network. | Testing load states and errors on throttled 3G networks and offline scenarios. |
Looking Ahead to 2026
First, the tooling is getting smarter but more opaque. In 2026, frameworks and bundlers will likely make more automatic, heuristic-based decisions about what to split and preload. Your job will shift from configuration to guiding those heuristics—providing hints via attributes or conventions rather than writing explicit import() statements everywhere.
Second, with the rise of edge computing and distributed deployment, the location of your chunks matters. A dynamic import might fetch a module from a CDN edge node 50ms away versus your origin server 300ms away. The setup will need to consider deployment geography and cache headers as part of the performance calculus.
Finally, I expect a tighter integration with browser primitives. We already have modulepreload. We might see a standard for declaring dynamic import dependencies in HTML or a native browser API for priority-based chunk streaming. The manual promise handling we do today might become a declarative attribute tomorrow. Your setup will need to be adaptable to these native capabilities as they emerge.
Frequently Asked Questions
Do dynamic imports work with server-side rendering (SSR)?
Yes, but they require careful setup. In SSR, you typically need to detect and preload all the dynamic chunks used during the server render so the client can hydrate seamlessly. Frameworks like Next.js and Nuxt handle this automatically, but in a custom setup, you’ll need to manage chunk manifest collection.
Can I use dynamic imports for third-party libraries?
You can, but you should be selective. Dynamically importing a massive library like a charting package only when needed is a great win. Dynamically importing lodash for a single function is likely a net loss due to network overhead. Always measure the real-world performance impact.
How do I debug or see what chunks are being created?
Use your bundler’s analysis tools. Webpack Bundle Analyzer and Vite’s built-in preview mode are essential. They show you the size and composition of every chunk. Also, use the Network tab in your browser’s DevTools with “Disable cache” and throttling enabled to see the real loading sequence.
How much do you charge compared to agencies?
I charge approximately 1/3 of what traditional agencies charge, with more personalized attention and faster execution. My model is built on direct collaboration and solving the specific technical strategy problems you have, not maintaining large retainers.
Is there a performance downside to too many small chunks?
Absolutely. Each chunk has HTTP overhead. If you create hundreds of tiny chunks, the browser can get bogged down managing all the concurrent requests and parsing many small files. There’s a balance. Aim for meaningful, user-centric chunks rather than fragmenting for its own sake.
Look, the goal isn’t to have dynamic imports everywhere. The goal is a fast, responsive application. Start with one thing. Pick your heaviest route or that massive admin panel that only 10% of users see. Split that. Implement a proper loading state. Measure the Core Web Vitals before and after. You’ll learn more from that one experiment than from any guide. In 2026, the code that never loads is the fastest code of all. Your job is to figure out what your user can wait for, and make that wait feel intentional, not broken.
