DateTime Axis

This example shows creation of a DateTime Axis, for rendering XY-series where either/both of X/Y dimensions can present time. This doesn't affect the input of data - format remains as {x: number, y: number} - however, DateTime-axes format their values from number to a date and time. This affects axis labels, markers and cursors.

A DateTime-Axis is created by specifying its TickStrategy. Here's how it looks when setting the Axis TickStrategy:

// Add an XY Chart
const chart = lightningChart().ChartXY({})
// Set the TickStrategy of the default X Axis to a DateTime TickStrategy
chart.getDefaultAxisX().setTickStrategy( AxisTickStrategies.DateTime )

The above mentioned examples will provide an Axis that will format its scale values to their DateTime-representations. This conversion relies on a reference date, further referred to as origin-date. This origin-date specifies the DateTime value that is equal to zero as a numeric representation. Incremental values will result in progressive DateTimes by milliseconds. For example, given origin-date is equal to the 1st of January 2002, 2PM, a numeric value of 7,200,000 would be translated to 1st of January 2002 4PM.

Translating this to how we can modify the origin date in our Axis, we can do this by adding a mutator to the setTickStrategy() method to modify the origin date:

// Define the origin-date. (y, m [0-11], d [1-31], h [0-23])
const originDate = new Date(2002, 0, 1, 13)
// Create DateTime AxisTickStrategy with specified originDate.
chart.getDefaultAxisX()
    .setTickStrategy(
        AxisTickStrategies.DateTime,
        // Use a mutator to set the origin date for this Axis' TickStrategy
        (tickStrategy) => tickStrategy.setDateOrigin(originDate)
    )

If this TickStrategy would be supplied to an X-Axis, it would effectively mean that its scale would start from 1st of January 2002 14PM, so a XY-point with coordinates { x: 0, y: 0 } would be formated as { x: "1.1.2002 14:00", y: 0 }.

It is worth mentioning that big DateTime-intervals can produce severe precision problems (eq. when zooming in). The only way to battle this is by reducing the distance of timestamps from the active origin-date.