format property
A format string for the axis label. The context is available as
format string variables. For example, you can use {text} to
insert the default formatted text. The recommended way of adding
units for the label is using text, for example {text} km.
To add custom numeric or datetime formatting, use {value} with
formatting, for example {value:.1f} or {value:%Y-%m-%d}.
See format string for more examples of formatting.
The default value is not specified due to the dynamic nature of the default implementation.
API Docs: https://api.highcharts.com/highcharts/yAxis.labels.format
Implementation
String? format;