#performance.chunkSplit

• Type: ChunkSplit
• Default: { strategy: 'split-by-experience' }

performance.chunkSplit configures the chunk splitting strategy. The type definition for ChunkSplit:

#chunkSplit.strategy

Rsbuild supports the following chunk splitting strategies:

• split-by-experience: an empirical splitting strategy, automatically splits some commonly used npm packages into chunks of moderate size.
• split-by-module: split by npm package granularity, each npm package corresponds to a chunk.
• split-by-size: automatically split according to module size.
• all-in-one: bundle all codes into one chunk.
• single-vendor: bundle all npm packages into a single chunk.
• custom: custom chunk splitting strategy.

#Type definition

The complete type definition for performance.chunkSplit:

type ForceSplitting = RegExp[] | Record<string, RegExp>;

interface BaseChunkSplit {
  strategy?:
    | 'split-by-module'
    | 'split-by-experience'
    | 'all-in-one'
    | 'single-vendor';
  override?: Rspack.OptimizationSplitChunksOptions;
  forceSplitting?: ForceSplitting;
}

interface SplitBySize extends BaseSplitRules {
  strategy: 'split-by-size';
  minSize?: number;
  maxSize?: number;
}

interface SplitCustom extends BaseSplitRules {
  strategy: 'custom';
  splitChunks?: SplitChunks;
}

type ChunkSplit = BaseChunkSplit | SplitBySize | SplitCustom;

#Default strategy

By default, Rsbuild uses the split-by-experience strategy. To use other chunk splitting strategies, specify them through the strategy option, for example:

export default {
  performance: {
    chunkSplit: {
      strategy: 'all-in-one',
    },
  },
};

#chunkSplit.minSize

• Type: number
• Default: 10000

When chunkSplit.strategy is split-by-size, you can specify the minimum size of a chunk via chunkSplit.minSize, the unit is bytes. The default value is 10000. For example:

export default {
  performance: {
    chunkSplit: {
      strategy: 'split-by-size',
      minSize: 20000,
    },
  },
};

#chunkSplit.maxSize

• Type: number
• Default: Number.POSITIVE_INFINITY

When chunkSplit.strategy is split-by-size, you can specify the maximum size of a chunk via chunkSplit.maxSize, the unit is bytes. The default value is Number.POSITIVE_INFINITY. For example:

export default {
  performance: {
    chunkSplit: {
      strategy: 'split-by-size',
      maxSize: 50000,
    },
  },
};

#chunkSplit.forceSplitting

• Type: RegExp[] | Record<string, RegExp>
• Default: []

Via chunkSplit.forceSplitting, you can specify the npm packages that need to be forced to split.

For example, split the axios library under node_modules into axios.js:

export default {
  performance: {
    chunkSplit: {
      forceSplitting: {
        axios: /node_modules[\\/]axios/,
      },
    },
  },
};

This is an easier way than configuring Rspack's splitChunks directly.

#chunkSplit.splitChunks

When chunkSplit.strategy is custom, you can specify the custom Rspack chunk splitting config via chunkSplit.splitChunks. This config will be merged with the Rspack splitChunks config (the cacheGroups config will also be merged). For example:

export default {
  performance: {
    chunkSplit: {
      strategy: 'custom',
      splitChunks: {
        cacheGroups: {
          react: {
            test: /node_modules[\\/](react|react-dom)[\\/]/,
            name: 'react',
            chunks: 'all',
          },
        },
      },
    },
  },
};

#chunkSplit.override

When chunkSplit.strategy is split-by-experience, split-by-module, split-by-size or single-vendor, you can specify the custom Rspack chunk splitting config via chunkSplit.override. This config will be merged with the Rspack splitChunks config (the cacheGroups config will also be merged). For example:

export default {
  performance: {
    chunkSplit: {
      override: {
        cacheGroups: {
          react: {
            test: /node_modules[\\/](react|react-dom)[\\/]/,
            name: 'react',
            chunks: 'all',
          },
        },
      },
    },
  },
};

#Targets

performance.chunkSplit only works when output.target is web. This means that when output.target is node or web-worker, performance.chunkSplit will not take effect.

Typically, Node bundles do not need to be split to optimize loading performance, if you need to split Node bundles, you can use the tools.rspack configuration to configure Rspack's optimization.splitChunks option:

export default {
  tools: {
    rspack: {
      optimization: {
        splitChunks: {
          // options
        },
      },
    },
  },
};