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

$3

``bash
npm i -g @vercel/ncc
`

$3

`bash
$ ncc
`
Eg:
`bash
$ 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 [opts]
run [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
`

$3

For testing and debugging, a file can be built into a temporary directory and executed with full source maps support with the command:

`bash
$ ncc run input.js
`

$3

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:

`json
{
"compilerOptions": {
"target": "es2015",
"moduleResolution": "node"
}
}
`

If typescript is found in devDependencies, that version will be used.

$3

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.

$3

`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:

`js
{
// 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