What is @vercel/ncc?
@vercel/ncc is a simple CLI tool used to compile a Node.js project into a single file, including all of its dependencies. This can be useful for reducing the complexity of deployment, improving startup time, and simplifying the distribution of Node.js applications.
What are @vercel/ncc's main functionalities?
Compile a Node.js project
This command compiles the Node.js project starting from 'src/index.js' and outputs the result to the 'dist' directory. The output will be a single JavaScript file that includes all dependencies.
ncc build src/index.js -o dist
Minify the output
This command compiles and minifies the Node.js project starting from 'src/index.js' and outputs the result to the 'dist' directory. Minification reduces the file size by removing unnecessary characters and whitespace.
ncc build src/index.js -o dist --minify
Source maps generation
This command compiles the Node.js project and generates source maps, which are useful for debugging. The source maps help map the minified code back to the original source code.
ncc build src/index.js -o dist --source-map
Watch mode
This command runs @vercel/ncc in watch mode, which means it will automatically recompile the project whenever a file changes. This is useful for development purposes.
ncc build src/index.js -o dist --watch
Other packages similar to @vercel/ncc
webpack
Webpack is a popular module bundler for JavaScript applications. It can bundle multiple modules into a single file or multiple files, and it offers a wide range of plugins and configuration options. Compared to @vercel/ncc, Webpack is more flexible and can be used for both frontend and backend projects, but it requires more configuration.
rollup
Rollup is a module bundler for JavaScript that focuses on ES6 modules. It is known for its tree-shaking feature, which removes unused code from the final bundle. Rollup is often used for libraries and smaller projects. Compared to @vercel/ncc, Rollup provides more control over the bundling process but may require additional plugins for certain features.
parcel
Parcel is a zero-configuration bundler that works out of the box. It supports both JavaScript and TypeScript and can handle various types of assets like CSS, HTML, and images. Parcel is designed to be easy to use and fast. Compared to @vercel/ncc, Parcel is more suitable for frontend projects and offers a simpler setup process.
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', {
cache: "./custom/cache/path" | false,
externals: ["externalpackage"],
filterAssetBase: process.cwd(),
minify: false,
sourceMap: false,
assetBuilds: false,
sourceMapBasePrefix: '../',
sourceMapRegister: true,
watch: false,
license: '',
target: 'es2015',
v8cache: false,
quiet: false,
debugLog: false
}).then(({ code, map, assets }) => {
console.log(code);
})
When watch: true
is set, the build object is not a promise, but has the following signature:
{
handler (({ err, code, map, assets }) => { ... })
rebuild (() => {})
void close ();
}
Caveats
- Files / assets are relocated based on a static evaluator. Dynamic non-statically analyzable asset loads may not work out correctly