Options

Defaults to searching for a default .swcrc file, but can be passed the path of any JS or JSON5 config file.

NOTE: This option does not affect loading of .swcrc files, so while it may be tempting to do configFile: "./foo/.swcrc", it is not recommended. If the given .swcrc is loaded via the standard file-relative logic, you'll end up loading the same config file twice, merging it with itself. If you are linking a specific config file, it is recommended to stick with a naming scheme that is independent of the "swcrc" name.

Defaults to path.resolve(opts.root, ".swcrc")

The working directory that all paths in the programmatic options will be resolved relative to.

Defaults to process.cwd().

The current active environment used during configuration loading. This value is used as the key when resolving "env" configs, and is also available inside configuration functions, plugins, and presets, via the api.env() function.

Defaults to process.env.SWC_ENV || process.env.NODE_ENV || "development"

The filename associated with the code currently being compiled, if there is one. The filename is optional, but not all of Swc's functionality is available when the filename is unknown, because a subset of options rely on the filename for their functionality.

The three primary cases users could run into are:

• The filename is exposed to plugins. Some plugins may require the presence of the filename.
• Options like "test", "exclude", and "ignore" require the filename for string/RegExp matching.
• .swcrc files are loaded relative to the file being compiled. If this option is omitted, Swc will behave as if swcrc: false has been set.

true will attempt to load an input sourcemap from the file itself, if it contains a //# sourceMappingURL=... comment. If no map is found, or the map fails to load and parse, it will be silently discarded.

If an object is provided, it will be treated as the source map object itself.

Defaults to true.

Destination path. Note that this value is used only to fix source path of source map files and swc does not write output to this path.

The initial path that will be processed based on the "rootMode" to determine the conceptual root folder for the current Swc project. This is used in two primary cases:

• The base directory when checking for the default "configFile" value
• The default value for "swcrcRoots".

Defaults to opts.cwd

This option, combined with the "root" value, defines how Swc chooses its project root. The different modes define different ways that Swc can process the "root" value to get the final project root.

"root" - Passes the "root" value through as unchanged. "upward" - Walks upward from the "root" directory, looking for a directory containing a swc.config.js file, and throws an error if a swc.config.js is not found. "upward-optional" - Walk upward from the "root" directory, looking for a directory containing a swc.config.js file, and falls back to "root" if a swc.config.js is not found.

"root" is the default mode because it avoids the risk that Swc will accidentally load a swc.config.js that is entirely outside of the current project folder. If you use "upward-optional", be aware that it will walk up the directory structure all the way to the filesystem root, and it is always possible that someone will have a forgotten swc.config.js in their home directory, which could cause unexpected errors in your builds.

Users with monorepo project structures that run builds/tests on a per-package basis may well want to use "upward" since monorepos often have a swc.config.js in the project root. Running Swc in a monorepo subdirectory without "upward", will cause Swc to skip loading any swc.config.js files in the project root, which can lead to unexpected errors and compilation failure.

If true, a file is parsed as a script instead of module.

The name to use for the file inside the source map object.

Defaults to path.basename(opts.filenameRelative) when available, or "unknown".

The sourceRoot fields to set in the generated source map, if one is desired.

true will enable searching for configuration files relative to the "filename" provided to Swc.

A swcrc value passed in the programmatic options will override one set within a configuration file.

Note: .swcrc files are only loaded if the current "filename" is inside of a package that matches one of the "swcrcRoots" packages.

Defaults to true as long as the filename option has been specified

By default, Babel will only search for .babelrc files within the "root" package because otherwise Babel cannot know if a given .babelrc is meant to be loaded, or if it's "plugins" and "presets" have even been installed, since the file being compiled could be inside node_modules, or have been symlinked into the project.

This option allows users to provide a list of other packages that should be considered "root" packages when considering whether to load .babelrc files.

For example, a monorepo setup that wishes to allow individual packages to have their own configs might want to do

Defaults to opts.root