Types

The public types you are most likely to read or annotate, generated from the library's TypeScript source.

The tables on this page are generated at build time from the TypeScript source, so they always match the published declarations.

StateChange

delta().stateChanges is a StateChange[]. It is a discriminated union on category:

type StateChange =
  | { category: 'data'; action: 'add' | 'remove' | 'update' }
  | {
      category: 'grain';
      action: 'split' | 'merge' | 'reaggregate' | 'change-reducer';
      previous: GrainDescription;
      next: GrainDescription;
    }
  | { category: 'encoding'; action: 'bind' | 'unbind' | 'remap'; channel: string }
  | { category: 'coordinate'; action: 'rescale' | 'reorient'; channel?: 'x' | 'y' }
  | { category: 'layout'; action: 'reorder' | 'rearrange' | 'reconnect' }
  | { category: 'attention'; action: 'enter' | 'exit' | 'shift'; target: 'focus' | 'highlight' }
  | { category: 'appearance'; action: 'restyle' | 'reshape'; property: string };

Narrow on category to read the extra fields:

for (const change of delta(from, to).stateChanges) {
  if (change.category === 'encoding') console.log(change.channel);
  if (change.category === 'grain') console.log(change.previous.groupby, '→', change.next.groupby);
}