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Marcin Wosinek
Marcin Wosinek

Posted on • Updated on • Originally published at

How to add live reload to esbuild server

In this article, I'll show how to set up a complete development server for esbuild. It's a replacement for the half-successful approach I had in the previous post.


This approach is based on esbuild-serve - a nice package that allows us to support two main use cases: building & development server. Let's install it first:

$ npm install esbuild-serve -D                                                         

> esbuild@0.9.7 postinstall /home/marcin/workspace/github/esbuild-tutorial/node_modules/esbuild-serve/node_modules/esbuild
> node install.js                                                                                                                                                                      

+ esbuild-serve@1.0.1                                                                                                                                                                  
added 3 packages from 1 contributor and audited 4 packages in 1.901s
found 0 vulnerabilities  
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esbuild configuration file

The configuration file we will use is a combination of the one developed in the previous post and the one presented in the esbuild-server documentation. esbuild.config.js:

#!/usr/bin/env node

import esbuildServe from "esbuild-serve";

    logLevel: "info",
    entryPoints: ["src/index.js"],
    bundle: true,
    outfile: "www/main.js",
  { root: "www" }
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We can run this file with:

  • node esbuild.config.js - for building
  • node esbuild.config.js -w - for development server

If you run those scripts and get:

$ node esbuild.config.js
(node:86676) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
import esbuildServe from "esbuild-serve";

SyntaxError: Cannot use import statement outside a module

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as I did, you will need to add to package.json:

  "type": "module",
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npm script update

Now, the final step is to replace the old npm scripts with calls to the current one:

  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "node esbuild.config.js",
    "start": "node esbuild.config.js -w"
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And it's working as expected:

$ npm run build

> esbuild-tutorial@1.0.0 build /home/marcin/workspace/github/esbuild-tutorial
> node esbuild.config.js

  www/main.js   151b 
  www/main.css   44b 

⚡ Done in 2ms

$ npm run start  

> esbuild-tutorial@1.0.0 start /home/marcin/workspace/github/esbuild-tutorial
> node esbuild.config.js -w

[watch] build finished, watching for changes...

Serving 🍛

Local → http://localhost:7000

Network →
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The repo, the branch.

You can check out my video course about esbuild.


We have seen how to set up a development server for esbuild. This setup has live reload & it's ready to use esbuild plugins. If you are interested in hearing when I have new esbuild content, you can sign up here.

Latest comments (0)


"I made 10x faster JSON.stringify() functions, even type safe"

☝️ Must read for JS devs