Function dxSqAt

src/interaction/findPointsAtX.ts:328–335

(idx: number)

      let right = insertionIndex;

      const dxSqAt = (idx: number): number | null => {
        const px = tupleData[idx][0];
        if (!Number.isFinite(px)) return null;
        const sx = xScale.scale(px);
        if (!Number.isFinite(sx)) return null;
        const dx = sx - xValue;
        return dx * dx;
      };

      while (left >= 0 || right < n) {
        while (left >= 0 && dxSqAt(left) === null) left--;