strip-whitespace

Strip inter-node whitespace in Astro and Svelte templates.

This repo contains:

• A Rust core that parses templates via tree-sitter and rewrites whitespace.
• A WASM wrapper used from JavaScript tooling.
• An unplugin plugin (Vite/Rollup/Webpack/etc).
• A tiny Astro integration that wires the Vite plugin into Astro.

How it works

This project strips inter-node whitespace (whitespace-only gaps between elements/expressions) in .astro and .svelte templates.

Importantly, this is a rewrite, not a simple "delete all whitespace text nodes" pass: in some cases we preserve the original formatting/newlines by moving whitespace into places that don’t create runtime text nodes. For example, when encountering <p>\n text, we may rewrite it to <p \n >text.

• The Rust core parses the template (via tree-sitter), finds whitespace-only gaps between nodes, and rewrites them.
• The JS plugins run this transform on the source templates using an unplugin transform hook with enforce: "pre", so the whitespace is removed before Astro/Svelte compilation.
• The unplugin also tries to reorder itself ahead of the framework compilers (by default, before astro:build and vite-plugin-svelte) so it consistently runs early.

Why not minify after build?

Minifying the built output (HTML emitted after compilation) can introduce hydration mismatches: the server-rendered HTML no longer matches what the client-side framework expects to hydrate (especially around text nodes / whitespace at component boundaries). By stripping whitespace before the template processor/compiler runs, the compiled output and hydration expectations stay in sync.

Install

Astro integration

astro add astro-strip-whitespace

# or: pnpm add -D astro-strip-whitespace
# or: npm i -D astro-strip-whitespace
# or: yarn add -D astro-strip-whitespace

Vite / other bundlers (unplugin)

pnpm add -D unplugin-strip-whitespace
# or: npm i -D unplugin-strip-whitespace
# or: yarn add -D unplugin-strip-whitespace

Usage

Astro

In astro.config.mjs / astro.config.ts:

import { defineConfig } from "astro/config";
import stripWhitespace from "astro-strip-whitespace";

export default defineConfig({
  integrations: [stripWhitespace()],
});

Vite

In vite.config.ts:

import { defineConfig } from "vite";
import stripWhitespace from "unplugin-strip-whitespace/vite";

export default defineConfig({
  plugins: [stripWhitespace()],
});

Rollup / Webpack / others

This project ships per-bundler entrypoints. Examples:

• unplugin-strip-whitespace/rollup
• unplugin-strip-whitespace/webpack
• unplugin-strip-whitespace/esbuild
• unplugin-strip-whitespace/nuxt
• unplugin-strip-whitespace/rspack
• unplugin-strip-whitespace/farm

Refer to the bundler-specific unplugin docs for the exact wiring pattern.

Development

This is a monorepo containing Rust crates and JavaScript packages:

strip-whitespace/
├── crates/             # [Rust] Rust crates excluding fuzz targets
│   ├── core/           #        Core Rust library for parsing & rewriting templates
│   └── wasm/           #        WASM wrapper for JavaScript integration
├── packages/           # [JS] JavaScript packages
│   ├── wasm/                       # WASM bindings generated from crates/wasm (private package)
│   ├── unplugin-strip-whitespace/  # Unplugin for Vite/Rollup/Webpack/etc
│   └── astro-strip-whitespace/     # Astro integration wrapper
├── examples/           # [JS] Example projects
│   └── e2e-astro/      #      End-to-end Astro test app
├── fixtures/           # Test fixtures
├── fuzz/               # [Rust] Fuzzing targets for Rust crates
├── scripts/            # Build and utility scripts
└── assets/             # Documentation assets (images, SVGs)

Key Components

• crates/core/: The core Rust library that uses tree-sitter to parse Astro and Svelte templates and rewrite whitespace.
• crates/wasm/: WASM bindings that expose the Rust core to JavaScript via wasm-pack.
• packages/unplugin-strip-whitespace/: An unplugin that works with Vite, Rollup, Webpack, esbuild, and other bundlers.
• packages/astro-strip-whitespace/: A tiny Astro integration that configures the Vite plugin for Astro projects.
• examples/e2e-astro/: An example Astro app for testing and development.

Common Commands

• pnpm test - run JS tests (Vitest)
• pnpm run build - build WASM + packages
• pnpm run build:e2e-astro / pnpm run dev:e2e-astro - run the Astro example app