function class()
{
     this.id = "id1";
     this.id2 = "id2";
     
     document.getElementById(this.id).onmouseover =   this.func("#000");

     this.func = function(val)
     {
          
          document.getElementById(this.id2).style.background = val;
     }
}

<div id="div1">Наведи сюда</div>
<div id="div2">чтобы раскрасить это</div>

<script>
function fuckingClass(rev, rel, color){
  this.func = function(){
    document.getElementById(rel).style.background = color;
  };
  document.getElementById(rev).onmouseover =   this.func;
};

var realizeThisShit = new fuckingClass('div1', 'div2', '#0FC');
</script>

_this = this;
 document.getElementById(this.id).onmouseover =  function(){_this.func()};