Server-side rendering (SSR) is a technique used to render web pages on the server and send the pre-rendered HTML to the client. It helps improve the performance and SEO of web applications.

Dynamic imports in JavaScript allow you to asynchronously import modules at runtime, which is useful for code-splitting and reducing the initial bundle size. However, when implementing SSR with dynamic imports, caching becomes a challenge. In this blog post, we will explore how to handle SSR caching with dynamic imports in JavaScript.

Table of Contents

• Why is caching important in SSR?
• Caching strategies for SSR with dynamic imports
  • Static dynamic imports
  • Custom caching solutions
• Summary

Why is caching important in SSR?

Caching plays a critical role in SSR to improve performance and reduce server load. When a web page is requested, the server checks if a cached version of the page exists. If it does, the server can return the pre-rendered HTML without re-rendering the entire page, resulting in faster response times.

Caching strategies for SSR with dynamic imports

When dealing with dynamic imports in SSR, we need to consider how to handle the caching of dynamically imported modules. Here are two common strategies:

Static dynamic imports

In this strategy, you can use static imports in the server-side code during the SSR process. By importing the modules statically, they become part of the server-side bundle, making them cached by default. This approach eliminates the need for separate caching handling.

Here’s an example of how you can use static dynamic imports in Node.js with Express:

// server.js
import express from 'express';
import { renderToString } from 'react-dom/server';

const app = express();

app.get('/', async (req, res) => {
  const { default: MyComponent } = await import('./components/MyComponent');

  const html = renderToString(<MyComponent />);
  res.send(html);
});

app.listen(3000, () => {
  console.log('Server started on port 3000');
});

Custom caching solutions

When static imports are not feasible or the modules need to be dynamically loaded at runtime, you can implement custom caching solutions. One approach is to use a caching library like lru-cache to store and retrieve imported modules based on a unique key, like the module’s URL or identifier.

Here’s an example using lru-cache to cache dynamically imported modules in Node.js:

// server.js
import express from 'express';
import { renderToString } from 'react-dom/server';
import LRU from 'lru-cache';

const app = express();
const cache = new LRU({ max: 100 });

app.get('/', async (req, res) => {
  const key = req.url;
  let MyComponent = cache.get(key);

  if (!MyComponent) {
    MyComponent = await import('./components/MyComponent');
    cache.set(key, MyComponent);
  }

  const html = renderToString(<MyComponent.default />);
  res.send(html);
});

app.listen(3000, () => {
  console.log('Server started on port 3000');
});

Summary

Caching is crucial for optimizing the performance and efficiency of SSR with dynamic imports in JavaScript. By using static dynamic imports or implementing custom caching solutions, you can effectively handle SSR caching and deliver faster rendering times to your users.

#tech #javascript