*upload

*upload turns an element into a file-upload trigger. It creates a hidden file input, lets the user pick files, and sends them with XMLHttpRequest and FormData.

• *keys selects accompanying host data.
• *params adds request metadata.
• *dry-run marks the upload request as dry-run.
• *response maps the parsed response into host data.

<button
  type="button"
  *upload="'/api/avatar'"
  accept="image/*"
  *keys="profile"
  *params="{ kind: 'avatar' }"
  *response="'result'">
  Upload avatar
</button>

Files are always sent as multipart/form-data. Sercrod also appends JSON fields named sercrod, data, and params.

Every successful response is mirrored to $response. Without *response, normal host data is not changed. *into remains a compatibility alias for whole-response placement.