The Loader Context#

The loader context represents the properties that are available inside of a loader assigned to the this property.

this.addContextDependency()#

function addContextDependency(directory: string): void;

Add the directory as a dependency for the loader results so that any changes to the files in the directory can be listened to.

this.addDependency()#

function addDependency(file: string): void;

Add a file as a dependency on the loader results so that any changes to them can be listened to. For example, sass-loader, less-loader use this trick to recompile when the imported style files change.

this.dependency()#

function dependency(file: string): void;

Alias of this.addDependency().

this.addMissingDependency()#

function addMissingDependency(file: string): void;

Add a non-existent file as a dependency on the loader results to make them listenable.

this.async()#

Tells Rspack that this loader will be called asynchronously. Returns this.callback.

this.cacheable()#

A function that sets the cacheable flag:

function cacheable(flag: boolean = true): void;

By default, the processing results of the loader are marked as cacheable. Calling this method and passing false turns off the loader's ability to cache processing results.

this.callback()#

function callback(
  err: Error | null,
  content: string | Buffer,
  sourceMap?: SourceMap,
  meta?: any,
): void;

A function that can be called synchronously or asynchronously in order to return multiple results. The expected arguments are:

1. The first parameter must be Error or null, which marks the current module as a compilation failure.
2. The second argument is a string or Buffer, which indicates the contents of the file after the module has been processed by the loader.
3. The third parameter is a source map that can be processed by the loader.
4. The fourth parameter is ignored by Rspack and can be anything (e.g. some metadata).

this.clearDependencies()#

function clearDependencies(): void;

Removes all dependencies of the loader result.

this.context#

The directory where the current module is located.

this.data#

A data object shared between the pitch and the normal phase.

this.emitError()#

function emitError(error: Error): void;

Emit an error. Unlike throw and this.callback(err) in the loader, it does not mark the current module as a compilation failure, it just adds an error to Rspack's Compilation and displays it on the command line at the end of this compilation.

this.emitWarning(warning: Error)#

function emitWarning(warning: Error): void;

Emit a warning.

this.emitFile()#

function emitFile(
  name: string,
  content: Buffer | string,
  sourceMap: SourceMap,
): void;

Emit a file.

this.getOptions(schema)#

Extracts the given loader option, accepting an optional JSON schema as an argument.

this.getResolve()#

function getResolve(options: ResolveOptions): resolve;

Create a resolver like this.resolve.

this.resolve()#

function resolve(
  context: string,
  request: string,
  callback: (err: Error | null, result: string) => void,
): void;

Resolve a request.

• context must be the absolute path to a directory. This directory is used as the starting location for resolving.
• request is the request to be resolved.
• callback is a callback function that gives the resolved path.

this.mode#

The value of mode is read when Rspack is run.

The possible values are: 'production', 'development', 'none'

this.target#

The value of target is read when Rspack is run.

this.resource#

The path string of the current module. For example '/abc/resource.js?query#hash'.

this.resourcePath#

The path string of the current module, excluding the query and fragment parameters. For example '/abc/resource.js?query#hash' in '/abc/resource.js'.

this.resourceQuery#

The query parameter for the path string of the current module. For example '?query' in '/abc/resource.js?query#hash'.

this.resourceFragment#

The fragment parameter of the current module's path string. For example '#hash' in '/abc/resource.js?query#hash'.

this.rootContext#

The directory where the project is configured in config

this.sourceMap#

Whether a source map should be generated.

this.getLogger()#

function getLogger(name?: string): void;

Get the logger of this compilation, through which messages can be logged.