`group` function

group.ts

import { Node } from '@motion-canvas/2d/lib/components';
import { all } from '@motion-canvas/core/lib/flow';
import {
  InterpolationFunction,
  TimingFunction,
  deepLerp,
  easeInOutCubic,
} from '@motion-canvas/core/lib/tweening';
import { Vector2 } from '@motion-canvas/core/lib/types';

type NodeType<A extends any[]> = A extends (infer U)[] ? U : never;

export class NodeGroup<T extends Node[]> {
  public constructor(private nodes: T) {
    for (const node of nodes) {
      for (const { key } of node) {
        if (!this.hasOwnProperty(key)) {
          // *points at butterfly* Is this reflection?
          (this as any)[key] = this.createHandler(key);
        }
      }
    }
  }

  public save() {
    for (const node of this.nodes) {
      node.save();
    }
  }

  public restore(
    duration: number,
    timingFunction: TimingFunction = easeInOutCubic,
  ) {
    return all(
      ...this.nodes.map((node) => node.restore(duration, timingFunction)),
    );
  }

  public *shift(
    value: Vector2,
    duration: number,
    timingFunction: TimingFunction = easeInOutCubic,
  ) {
    yield* all(
      ...this.nodes.map((node) =>
        node.position(node.position().add(value), duration, timingFunction),
      ),
    );
  }

  private createHandler(key: string) {
    return (
      value: any,
      duration: number,
      timingFunction: TimingFunction = easeInOutCubic,
      interpolationFunction: InterpolationFunction<any> = deepLerp,
    ) => {
      return all(
        ...this.nodes.map((node) =>
          (node as any)[key](
            value,
            duration,
            timingFunction,
            interpolationFunction,
          ),
        ),
      );
    };
  }
}

export function group<T extends Node[]>(...nodes: T) {
  return new ChainableGroup(nodes) as NodeGroup<T> & NodeType<T>;
}

Note that this is a really rough proof of concept with a bunch of hardcoded exceptions (like save and restore). This would obviously need more work, should this ever make it's way into the core (not saying that it will). But it works well enough for my own projects, so I thought it would be useful to share.