ncc
Simple CLI for compiling a Node.js module into a single file,
together with all its dependencies, gcc-style.
Motivation
- Publish minimal packages to npm
- Only ship relevant app code to serverless environments
- Don't waste time configuring bundlers
- Generally faster bootup time and less I/O overhead
- Compiled language-like experience (e.g.:
go)
Design goals
- Zero configuration
- TypeScript built-in
- Only supports Node.js programs as input / output
- Support all Node.js patterns and npm modules
Usage
Installation
npm i -g @vercel/ncc
Usage
$ ncc <cmd> <opts>
Eg:
$ ncc build input.js -o dist
If building an .mjs or .js module inside a "type": "module" package boundary, an ES module output will be created automatically.
Outputs the Node.js compact build of input.js into dist/index.js.
Note: If the input file is using a .cjs extension, then so will the corresponding output file.
This is useful for packages that want to use .js files as modules in native Node.js using
a "type": "module" in the package.json file.
Commands:
build <input-file> [opts]
run <input-file> [opts]
cache clean|dir|size
help
version
Options:
-o, --out [dir] Output directory for build (defaults to dist)
-m, --minify Minify output
-C, --no-cache Skip build cache population
-s, --source-map Generate source map
-a, --asset-builds Build nested JS assets recursively, useful for
when code is loaded as an asset eg for workers.
--no-source-map-register Skip source-map-register source map support
-e, --external [mod] Skip bundling 'mod'. Can be used many times
-q, --quiet Disable build summaries / non-error outputs
-w, --watch Start a watched build
-t, --transpile-only Use transpileOnly option with the ts-loader
--v8-cache Emit a build using the v8 compile cache
--license [file] Adds a file containing licensing information to the output
--stats-out [file] Emit webpack stats as json to the specified output file
--target [es] ECMAScript target to use for output (default: es2015)
Learn more: https://webpack.js.org/configuration/target
-d, --debug Show debug logs
Execution Testing
For testing and debugging, a file can be built into a temporary directory and executed with full source maps support with the command:
$ ncc run input.js
With TypeScript
The only requirement is to point ncc to .ts or .tsx files. A tsconfig.json
file is necessary. Most likely you want to indicate es2015 support:
{
"compilerOptions": {
"target": "es2015",
"moduleResolution": "node"
}
}
If typescript is found in devDependencies, that version will be used.
Package Support
Some packages may need some extra options for ncc support in order to better work with the static analysis.
See package-support.md for some common packages and their usage with ncc.
Programmatically From Node.js
require('@vercel/ncc')('/path/to/input', {
// provide a custom cache path or disable caching
cache: "./custom/cache/path" | false,
// externals to leave as requires of the build
externals: ["externalpackage"],
// directory outside of which never to emit assets
filterAssetBase: process.cwd(), // default
minify: false, // default
sourceMap: false, // default
assetBuilds: false, // default
sourceMapBasePrefix: '../', // default treats sources as output-relative
// when outputting a sourcemap, automatically include
// source-map-support in the output file (increases output by 32kB).
sourceMapRegister: true, // default
watch: false, // default
license: '', // default does not generate a license file
target: 'es2015', // default
v8cache: false, // default
quiet: false, // default
debugLog: false // default
}).then(({ code, map, assets }) => {
console.log(code);
// Assets is an object of asset file names to { source, permissions, symlinks }
// expected relative to the output code (if any)
})
When watch: true is set, the build object is not a promise, but has the following signature:
{
// handler re-run on each build completion
// watch errors are reported on "err"
handler (({ err, code, map, assets }) => { ... })
// handler re-run on each rebuild start
rebuild (() => {})
// close the watcher
void close ();
}
Caveats
- Files / assets are relocated based on a static evaluator. Dynamic non-statically analyzable asset loads may not work out correctly
