The concept is to draw a div with absolute position inside of "starting point" and rotate it on an angle between 2 points:
// a,b  = jquery results i.e. a=$('#smile1'), b=$('#smile2'),
  function dist(a,b) {
      let o1 = a.offset(), o2 = b.offset();
       return Math.sqrt(Math.pow(o1.top  - o2.top,2) + Math.pow(o1.left - o2.left,2));
    }
    function angle(a, b) {
       let ao = a.offset(), bo = b.offset();
           dx = ao.left-bo.left, dy = ao.top-bo.top;
       return Math.PI + Math.atan2(dy, dx);
    }
    function drawConnection(a,b) {
       $('.line').remove();
       let d = dist(a,b);
       a.removeClass('first');
       let ang = d<10 
           ? 0
           : (angle(a,b) * 180)/ Math.PI;
       a.append(
          $('<div>').addClass('line')
              .css({
                  width: Math.round(d) +'px',
                  transform: 'rotate(' + Math.round(ang) + 'deg)'
              })
       );
       return ang;
    }
CSS for the line should be:
.line {
   position: absolute;
   transform-origin: top left; // to make it rotate around top-left
   border-top: solid 2px blue; // set any color
   top: 10px; // center of your "smile"
   left: 10px;
}
Here is the working example