Method _getCalculatedZIndex

src/cdk/table/sticky-styler.ts:413–432

* Calculate what the z-index should be for the element, depending on what directions (top, * bottom, left, right) have been set. It should be true that elements with a top direction * should have the highest index since these are elements like a table header. If any of those * elements are

(element: HTMLElement)

   * elements.
   */
  _getCalculatedZIndex(element: HTMLElement): string {
    const zIndexIncrements = {
      top: 100,
      bottom: 10,
      left: 1,
      right: 1,
    };

    let zIndex = 0;
    // Use `Iterable` instead of `Array` because TypeScript, as of 3.6.3,
    // loses the array generic type in the `for of`. But we *also* have to use `Array` because
    // typescript won't iterate over an `Iterable` unless you compile with `--downlevelIteration`
    for (const dir of STICKY_DIRECTIONS as Iterable<StickyDirection> & StickyDirection[]) {
      if (element.style[dir]) {
        zIndex += zIndexIncrements[dir];
      }
    }

    return zIndex ? `${zIndex}` : '';
  }

  /** Gets the widths for each cell in the provided row. */
  _getCellWidths(row: HTMLElement, recalculateCellWidths = true): number[] {