code: function applyStyleOnLoad(reference, popper, options, modifierOptions, state) {
    // compute reference element offsets
    const referenceOffsets = getReferenceOffsets(state, popper, reference, options.positionFixed);
  
    // compute auto placement, store placement inside the data object,
    // modifiers will be able to edit `placement` if needed
    // and refer to originalPlacement to know the original value
    const placement = computeAutoPlacement(options.placement, referenceOffsets, popper, reference, options.modifiers.flip.boundariesElement, options.modifiers.flip.padding);
  
    popper.setAttribute('x-placement', placement);
  
    // Apply `position` to popper before anything else because
    // without the position applied we can't guarantee correct computations
    setStyles(popper, { position: options.positionFixed ? 'fixed' : 'absolute' });
  
    return options;
  }
docs: Set the x-placement attribute before everything else because it could be used
  to add margins to the popper margins needs to be calculated to get the
  correct popper offsets.
  @method
  @memberof Popper.modifiers
  @param {HTMLElement} reference - The reference element used to position the popper
  @param {HTMLElement} popper - The HTML element used as popper
  @param {Object} options - Popper.js options