createDataLoader

Creates a klinecharts DataLoader from a Datafeed instance, wiring history pagination and real-time subscription into the chart.

function createDataLoader(
  datafeed: Datafeed,
  dispatch: Dispatch<KlinechartsUIAction>,
): DataLoader;

Behavior

klinecharts request	Action
"init"	Loads the latest ~1000 bars (to=Date.now(), from=0), saves oldestTimestamp, increments currentGen
"forward"	Loads bars older than oldestTimestamp - 1 for left-scroll pagination
"backward"	Ignored (real-time is handled via subscribeBar)

Race-condition protection: each "init" increments an internal generation counter. If a "forward" request resolves after a newer "init" has started, its result is discarded — so switching symbols rapidly never mixes data.

Usage

Memoize it so the loader is stable across renders:

function ChartView() {
  const { state, dispatch, datafeed } = useKlinechartsUI();

  const dataLoader = useMemo(
    () => createDataLoader(datafeed, dispatch),
    [datafeed, dispatch],
  );

  return (
    <KLineChart
      dataLoader={dataLoader}
      symbol={state.symbol ?? undefined}
      period={state.period}
      locale={state.locale}
      timezone={state.timezone}
      styles={state.theme}
      onReady={(chart) => dispatch({ type: "SET_CHART", chart })}
    />
  );
}