Function emit

src/interaction/createZoomState.ts:104–119

()

  let normalizedMaxSpan = Math.max(minSpan, maxSpan);

  const emit = (): void => {
    const next: ZoomRange = { start, end };
    if (
      lastEmitted !== null &&
      lastEmitted.start === next.start &&
      lastEmitted.end === next.end
    ) {
      return;
    }

    lastEmitted = copyRange(next);

    // Emit to a snapshot so additions/removals during emit don't affect this flush.
    const snapshot = Array.from(listeners);
    for (const cb of snapshot) cb({ start, end });
  };

  const toAnchor = (nextStart: number, nextEnd: number, spec?: ZoomRangeAnchor): { readonly center: number; readonly ratio: number } | undefined => {
    if (!spec) return undefined;