Function getNodeAssetAttributes

packages/vite/src/node/assetSource.ts:123–185

(
  node: DefaultTreeAdapterMap['element'],
  additionalAssetSources?: Record<string, HtmlAssetSource>,
)

 * Given a HTML node, find all attributes that references an asset to be processed
 */
export function getNodeAssetAttributes(
  node: DefaultTreeAdapterMap['element'],
  additionalAssetSources?: Record<string, HtmlAssetSource>,
): HtmlAssetAttribute[] {
  const defaults = DEFAULT_HTML_ASSET_SOURCES[node.nodeName]
  const additional = additionalAssetSources?.[node.nodeName]

  if (!defaults && !additional) return []

  const attributes: Record<string, string> = {}
  for (const attr of node.attrs) {
    attributes[getAttrKey(attr)] = attr.value
  }

  // If the node has a `vite-ignore` attribute, remove the attribute and early out
  // to skip processing any attributes
  if ('vite-ignore' in attributes) {
    return [
      {
        type: 'remove',
        key: 'vite-ignore',
        value: '',
        attributes,
        location: node.sourceCodeLocation!.attrs!['vite-ignore'],
      },
    ]
  }

  const actions: HtmlAssetAttribute[] = []
  function handleAttributeKey(
    key: string,
    type: 'src' | 'srcset',
    filter?: (data: HtmlAssetSourceFilterData) => boolean,
  ) {
    const value = attributes[key]
    if (!value) return
    if (filter && !filter({ key, value, attributes })) return
    const location = node.sourceCodeLocation!.attrs![key]
    actions.push({ type, key, value, attributes, location })
  }

  // Run matching for default asset sources
  if (defaults) {
    defaults.srcAttributes?.forEach((key) =>
      handleAttributeKey(key, 'src', defaults.filter),
    )
    defaults.srcsetAttributes?.forEach((key) =>
      handleAttributeKey(key, 'srcset', defaults.filter),
    )
  }

  // Run matching for additional asset sources
  if (additional) {
    additional.srcAttributes?.forEach((key) =>
      handleAttributeKey(key, 'src', additional.filter),
    )
    additional.srcsetAttributes?.forEach((key) =>
      handleAttributeKey(key, 'srcset', additional.filter),