(P)reacting on the server side?

3 min readOct 1, 2018

It takes time to realize Server-side rendering is amazing.😁 It was the same for me. You get a ton of benefits with it. Mainly, first meaningful paint of the webpage is quick. It still has to download the js to make it interactive. But, users will not be staring at white (empty) pages for long.

As you might know, Preact is the 3KB alternative to React. It is a bit faster than React and very less in size. The API is mostly same and easy to adapt if you are coming from React.

Let’s see how we can do that using Node on the server. We will be using preact-router for the routing at the client side.

This is the repo that I have created if you want to follow along.

`mkdir`

Create an empty directory and npm init it!

Now, we install the necessary things.

yarn add preact preact-router preact-render-to-string expressyarn add -D webpack webpack-cli babel-core babel-cli babel-loader 
babel-preset-env babel-plugin-transform-react-jsx babel-register

There are a few new packages that are helping us here.

preact-render-to-string - This will help us render the App to string so that we can include this in the HTML that we send out to the client.

babel-register - helps in transpiling ES6 code at runtime on the server.

Webpack 🔷

Look at the repo to see how the project is structured. client folder contains the Preact code and the webpack is configured to generate a build from that folder to a file.

module.exports = {
  entry: {
    app: "./client/index.js"
  },
  output: {
    path: path.join(__dirname, "dist"),
    filename: "[name].js"
  },
  module: {
    rules: [
      {
        test: /\\.js$/,
        loader: "babel-loader",
      }
    ]
  }
};

Server 🚀

The main file is index.js here where it requires babel to be present at runtime and help in transpiling code.

require("babel-register")({
  presets: ["env"],
  "plugins": [
    ["transform-react-jsx", { "pragma": "h" }]
  ],
});
require("./server");

{"pragma": "h"} is given as an option to the transform-react-jsx babel plugin because we are dealing with Preact and createElement is h() in it.

Babel can do the magic once you tell this to it. ✨

Now we have server.js where the rendering logic is present.

const express = require("express");
const { h } = require("preact");
const renderToString = require("preact-render-to-string");
const path = require("path");
const chalk = require("chalk");const App = require('./client/App');const app = express();
const port = 8080;app.use(express.static(path.join(__dirname, "dist")));app.listen(port);	app.get("*", (req, res) => {
  const html = renderToString(<App />);  res.send(`
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Preact SSR</title>
</head>
<body>
  <div id="app">${html}</div>
  <script src="./app.js"></script>
</body>
</html>
    `);
});console.log(chalk.blue(`Server started at <http://localhost>:${port}`));

See how we are generating html and including it in res.send(). We include the Webpack output, app.js, as a script tag. As we have set express.static as the dist directory, Express will serve that folder as well.

That’s it.

🏃

Run node index.js to see the magic. 🎉

Take Care!

(P)reacting on the server side?

mkdir

Webpack 🔷

Server 🚀

🏃

Written by Aravind Balla

`mkdir`