Candlestick

The simple version

A wick and a body per day. The same structure with almost no styling: a good place to start your own.

How it’s built

Each day here is one object, so the Plot is given the whole list at once with rows={days()} instead of a list per value. A slat then reads its own day as d.open, d.close, d.low and d.high, and draws two Bars in the same place:

• a thin one from low to high, which is the wick,
• a thicker one from open to close, which is the body.

A Bar whose to is below its from runs the other way on its own, so a falling day needs no special case; only the colour changes, from a class on the slat. nice() turns the month’s lowest and highest prices into a round scale and the ticks to go with it.

The gallery version adds:

• A crosshair that is a Plot of zero or one slat. While no day is picked, slats={0} means there is nothing in the page at all. Point at a day and that one slat draws a dashed Tick at its close and a Label with the price. See interaction for why one slat beats one per day.
• A readout above the chart. The day under the pointer is kept in a signal, and the numbers above the chart are read from it, so the chart and the text never disagree.