esbuild-svelte

Plugin to compile svelte components for bundling with esbuild.

Install

Install both this plugin and esbuild (esbuild must be above 0.9.6).

A simple build script looks like

import esbuild from "esbuild";
import sveltePlugin from "esbuild-svelte";

esbuild
  .build({
    entryPoints: ["app.js"],
    mainFields: ["svelte", "browser", "module", "main"],
    bundle: true,
    outfile: "out.js",
    plugins: [sveltePlugin()],
    logLevel: "info",
  })
  .catch(() => process.exit(1));

The example folder of this repository is a great starting off point for a "complete" project.

CSS Output

By default, esbuild-svelte emits external css files from Svelte for esbuild to process. If this isn't desired, use a configuration that turns off external css output and instead includes it in the javascript output. For example: sveltePlugin({compilerOptions: {css: true}})

Typescript and Other Svelte Preprocessing

In order to support Typescript and other languages that require preprocessing before being fed into the Svelte compiler, simply add the preprocessor to the preprocess option (which accepts both a single preprocessor or an array of them). The example script below is a great place to start.

import esbuild from "esbuild";
import esbuildSvelte from "esbuild-svelte";
import sveltePreprocess from "svelte-preprocess";

esbuild
  .build({
    entryPoints: ["index.js"],
    mainFields: ["svelte", "browser", "module", "main"],
    bundle: true,
    outdir: "./dist",
    plugins: [
      esbuildSvelte({
        preprocess: sveltePreprocess(),
      }),
    ],
  })
  .catch(() => process.exit(1));

Advanced

For incremental or watch build modes, esbuild-svelte will automatically cache files if they haven't changed. This allows esbuild to skip the Svelte compiler for those files altogether, saving time. Setting cache: false will disable this file level cache if an issue arises (please report).

You can see the full API for this plugin here, which includes support for Svelte's compiler options, preprocessing API, and more.

Developing

Clone, npm install, npm link and it's good to go! Releases are automated (with the right permissions), just by running npm version patch|minor|major.