Rehash

A CLI tool for cache-busting static assets by embedding hashes in filenames and updating references.

Features

• Renames files by embedding a hash in filename (e.g., file.js → file.rehash--abc123...--rehash.js)
• Updates references in HTML and JS files to point to the newly renamed files
• Supports glob patterns for selecting files to rehash and update
• Handles source maps (.map files) automatically
• Multiple passes ensure all references are updated correctly

Installation

npm install -g rehash

Or use locally in your project:

npm install rehash --save-dev

Usage

rehash [options] [directory]

Arguments

• directory - Directory to process (defaults to current working directory). All globs are resolved relative to this directory.

Options

| Option | Short | Description | Default | | ----------------- | ----- | ------------------------------------------------ | ------------------ | | --rehash <glob> | -r | Glob pattern for files to rehash | See defaults below | | --update <glob> | -u | Glob pattern for files to update with new hashes | See defaults below | | --ignore <glob> | -i | Glob pattern for files to ignore | None | | --help | -h | Show help message | N/A |

Default Behavior

If no --rehash nor --update options are provided, rehash uses sensible defaults:

Files to rehash:

**/*.css
**/*.eot
**/*.gif
**/*.ico
**/*.jpeg
**/*.jpg
**/*.js
**/*.json
**/*.png
**/*.svg
**/*.swf
**/*.ttf
**/*.wasm
**/*.webp
**/*.woff
**/*.woff2

Files to update:

**/*.html
**/*.js

Examples

Basic usage (current directory)

rehash

Process a specific directory

rehash dist/

Custom file patterns

# Only rehash JS and CSS files, don't update any files
rehash --rehash "**/*.js" --rehash "**/*.css"

# Rehash all assets and update HTML files
rehash --rehash "**/*.{js,css,png,jpg}" --update "**/*.html"

# Ignore certain files from rehashing and from updating
rehash --ignore "submodule/**"

Multiple patterns

rehash \
  --rehash "**/*.js" \
  --rehash "**/*.css" \
  --update "**/*.html" \
  --update "**/index.js" \
  --ignore "**/node_modules/**"

How It Works

1. Rehash Phase: Files matching the rehash glob patterns are renamed with a hash embedded in the filename (format: filename.rehash--[hash]--rehash.extension)
2. Update Phase: Files matching the update glob patterns have their content scanned for references to the original filenames, which are replaced with the new hashed filenames
3. Multiple Passes: The tool runs multiple passes until no more changes are detected, ensuring all references are properly updated

File Naming Format

When a file is rehashed, it follows this naming convention:

original-name.rehash--[sha256-hash]--rehash.extension

For example:

script.js → script.rehash--a1b2c3d4e5f6...--rehash.js
image.png → image.rehash--f7e8d9c0b1a2...--rehash.png

Supported Reference Formats

The tool updates references in the following formats:

• Double quotes: "file.js"
• Single quotes: 'file.js'
• Backticks: `file.js`
• Relative paths with or without ./ prefix

FAQ

Rehash fails on my big complex project with many dependencies

Rehash is designed for simple static sites. It may not handle highly complex projects. You're welcome to open a PR if the fix is simple and doesn't introduce significant complexity, but such cases are generally out of scope for this tool.

I have dependency cycles in my project

Rehash will happily follow your dependency cycles indefinitely.

Can I use rehash with build tools like Webpack or Vite?

Please don't. These tools have their own asset handling and cache-busting mechanisms.

License

GNU Affero General Public License v3.0 - see LICENSE for details.