Function combineSourcemapsIfExists

packages/vite/src/node/plugins/css.ts:1896–1913

(
  filename: string,
  map1: ExistingRawSourceMap | { mappings: '' } | undefined,
  map2: ExistingRawSourceMap | { mappings: '' } | undefined,
)

}

function combineSourcemapsIfExists(
  filename: string,
  map1: ExistingRawSourceMap | { mappings: '' } | undefined,
  map2: ExistingRawSourceMap | { mappings: '' } | undefined,
): ExistingRawSourceMap | { mappings: '' } | undefined {
  if (!map1 || !map2) {
    return map1
  }
  if (map1.mappings === '' || map2.mappings === '') {
    return { mappings: '' }
  }
  return combineSourcemaps(filename, [
    // type of version property of ExistingRawSourceMap is number
    // but it is always 3
    map1 as RawSourceMap,
    map2 as RawSourceMap,
  ]) as ExistingRawSourceMap
}

const viteHashUpdateMarker = '/*$vite$:1*/'
const viteHashUpdateMarkerRE = /\/\*\$vite\$:\d+\*\//