Method transformMutate

src/service/fixed-layer.js:285–312

* Apply or reset transform style to fixed elements. The existing transition, * if any, is disabled when custom transform is supplied. * @param {?string} transform

(transform)

   * @param {?string} transform
   */
  transformMutate(transform) {
    // Unfortunately, we can't do anything with sticky elements here. Updating
    // `top` in animation frames causes reflow on all platforms and we can't
    // determine whether an element is currently docked to apply transform.
    if (transform) {
      // Apply transform style to all fixed elements
      this.elements_.forEach((e) => {
        if (e.fixedNow && e.top) {
          setStyle(e.element, 'transition', 'none');
          if (e.transform && e.transform != 'none') {
            setStyle(e.element, 'transform', e.transform + ' ' + transform);
          } else {
            setStyle(e.element, 'transform', transform);
          }
        }
      });
    } else {
      // Reset transform style to all fixed elements
      this.elements_.forEach((e) => {
        if (e.fixedNow && e.top) {
          setStyles(e.element, {
            transform: '',
            transition: '',
          });
        }
      });
    }
  }

  /**
   * Adds the element directly into the fixed/sticky layer, bypassing discovery.