Streaming

Every layer exposes setData(...). Create it once with the "dynamic" buffer hint, then push new arrays and re-render.

const line = plot.addLine({ x, y, renderType: "dynamic" });

function frame() {
  line.setData(x, y);   // re-uploads the GPU buffers
  plot.render();
  requestAnimationFrame(frame);
}

renderType maps to the WebGL buffer-usage hint (STATIC_DRAW vs DYNAMIC_DRAW). It is a performance hint only — setData works either way.

Candlesticks

Live price charts have two distinct updates, so candlesticks get dedicated methods that avoid re-uploading the whole series:

candles.updateLast({ open, high, low, close });  // the forming bar
candles.appendCandle(x, { open, high, low, close }); // roll to a new bar

Cost

setData re-uploads; it does not reallocate when the length is unchanged. For very large series, keep the arrays alive and mutate them in place (as the demo above does with copyWithin) rather than allocating each frame.

Lines decimate to about two points per pixel column when zoomed out, on the GPU above 200k points, so a million-point series stays interactive without any work on your side. Set decimate: false to draw every vertex.