#FlowLoader

The FlowLoader removes Flow type annotations from JavaScript files, ensuring they can be processed by loaders that do not support Flow syntax. It should be positioned before other loaders (e.g. builtin:swc-loader) to prevent parsing errors when encountering Flow-specific code.

#Options

type FlowLoaderOptions = {
  all?: boolean;
  ignoreUninitializedFields?: boolean;
  pretty?: boolean;
  removeEmptyImports?: boolean;
};

#all

• Type: boolean
• Default: false

If true, bypasses looking for an @flow pragma comment before parsing.

#ignoreUninitializedFields

• Type: boolean
• Default: false

If true, removes uninitialized class fields (foo;, foo: string;) completely rather than only removing the type.

#pretty

• Type: boolean
• Default: false

If true, removes types completely rather than replacing with spaces. This may require using source maps.

#removeEmptyImports

• Type: boolean
• Default: true

If true, removes empty import statements (import {} from 'flow-typed-module';) which were only used for importing flow types.

#Example

module.exports = {
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        use: {
          loader: "@callstack/repack/flow-loader",
          options: { all: true },
        },
        type: "javascript/auto",
      },
    ],
  },
};