modal.html

<div id="modal-id" class="modal modal-open">
  <button class="modal-close">X</button>
</div>

modal.js

$('.modal-open').each( function(){
  $(this).on( 'click', function(){
    var target = $(this).data( 'target' );
    var modal = document.getElementByID( target );
    $(modal).fadeIn();
    // if you'd like to change diplay property to 'inline-block' or 'flex', write below
    // $(modal).fadeIn().css( 'display', 'flex' ); 
    return false;
  });
});

$('.modal-close').on( 'click', function(){
  $('.modal').fadeOut();
});

target.html

<a href="#" data-target="modal-01">
  <!-- Open modal if you click this aea -->
</a>
<a href="#" data-target="modal-02">
  <!-- Open modal if you click this aea -->
</a>