script.js

$(document).ready(function() {
 
  
  $('.open').click(function () {
    if ($('body').hasClass('open-curtains')) {
      $('body').removeClass('open-curtains');
    } else {
      $('body').addClass('open-curtains');
    }
  });
 
});

var btn = document.querySelector( '.btn' );

var btnFront = btn.querySelector( '.btn-front' ),
    btnYes = btn.querySelector( '.btn-back .yes' ),
    btnNo = btn.querySelector( '.btn-back .no' );

btnFront.addEventListener( 'click', function( event ) {
  var mx = event.clientX - btn.offsetLeft,
      my = event.clientY - btn.offsetTop;

  var w = btn.offsetWidth,
      h = btn.offsetHeight;
	
  var directions = [
    { id: 'top', x: w/2, y: 0 },
    { id: 'right', x: w, y: h/2 },
    { id: 'bottom', x: w/2, y: h },
    { id: 'left', x: 0, y: h/2 }
  ];
  
  directions.sort( function( a, b ) {
    return distance( mx, my, a.x, a.y ) - distance( mx, my, b.x, b.y );
  } );
  
  btn.setAttribute( 'data-direction', directions.shift().id );
  btn.classList.add( 'is-open' );

} );

btnYes.addEventListener( 'click', function( event ) {	
  btn.classList.remove( 'is-open' );
} );

btnNo.addEventListener( 'click', function( event ) {
  btn.classList.remove( 'is-open' );
} );

function distance( x1, y1, x2, y2 ) {
  var dx = x1-x2;
  var dy = y1-y2;
  return Math.sqrt( dx*dx + dy*dy );
}