1. A computer-implemented method comprising: receiving a request from a client to access data in a structured document while the structured document is being parsed by a computing device in a serial manner from beginning to end of the structured document, the parsing producing a data object in a memory which changes as the parsing progresses; in response to the request, and while the structured document is being parsed, determining that the data is not yet available in a portion of the data object by ascertaining a state of the parsing; and when the data becomes available in the data object, and before the parsing has completed, performing the requested access on the portion of the data object, returning any requested data to the client, and deleting the portion of the data object as parsing progresses.