Function resolvePackageEntry

packages/vite/src/node/plugins/resolve.ts:906–995

(
  id: string,
  { dir, data, setResolvedCache, getResolvedCache }: PackageData,
  options: InternalResolveOptions,
  externalize?: boolean,
)

}

export function resolvePackageEntry(
  id: string,
  { dir, data, setResolvedCache, getResolvedCache }: PackageData,
  options: InternalResolveOptions,
  externalize?: boolean,
): string | undefined {
  const { file: idWithoutPostfix, postfix } = splitFileAndPostfix(id)

  const cached = getResolvedCache(class="st">'.', options)
  if (cached) {
    return cached + postfix
  }

  try {
    let entryPoint: string | undefined

    class="cm">// resolve exports field with highest priority
    class="cm">// using https://github.com/lukeed/resolve.exports
    if (data.exports) {
      entryPoint = resolveExportsOrImports(
        data,
        class="st">'.',
        options,
        class="st">'exports',
        externalize,
      )
    }

    class="cm">// fallback to mainFields if still not resolved
    if (!entryPoint) {
      for (const field of options.mainFields) {
        if (typeof data[field] === class="st">'string') {
          entryPoint = data[field]
          break
        } else if (field === class="st">'browser') {
          const browser = data[field]
          if (isObject(browser) && browser[class="st">'.']) {
            entryPoint = browser[class="st">'.']
            break
          }
        }
      }
    }
    entryPoint ||= data.main

    class="cm">// try default entry when entry is not define
    class="cm">// https://nodejs.org/api/modules.html#all-together
    const entryPoints = entryPoint
      ? [entryPoint]
      : [class="st">'index.js', class="st">'index.json', class="st">'index.node']

    for (let entry of entryPoints) {
      class="cm">// make sure we don't get scripts when looking for sass
      let skipPackageJson = false
      if (
        options.mainFields[0] === class="st">'sass' &&
        !options.extensions.includes(path.extname(entry))
      ) {