(function(){
  'use strict';

  var Item = function(){
    this.ele = document.getElementById('item');
    this.is_toggle = false;
    this.x = parseInt(this.ele.getAttribute('x'));
    this.y = parseInt(this.ele.getAttribute('y'));
    this.dx = 6;
    this.dy = 1;
    this.t = 0;
    console.log(this.x + ':' + this.y);
  }
  Item.prototype = {
    self : this,
    handler : function(e){
      var src;
      e = e || window.event;
      src = e.target || e.srcElement;
      if(this.is_toggle){
        src.setAttribute('class', 'off');
        src.setAttribute('style', 'fill:#222222;');
        src.innerHTML = 'OFF';
        this.dx = -1;
      } else {
        src.setAttribute('class', 'on');
        src.setAttribute('style', 'fill:#999999');
        src.innerHTML = 'ON';
        src.setAttribute('transform', 'translate(30)');
        this.dx = 1;
      }
      this.is_toggle = !this.is_toggle;
      console.log(src.innerHTML);
    },
    move : function(){
  /*
      this.x += this.dx;
      this.y += this.dy;
  */
      this.t++;
      this.x = Math.sin(this.t/30)*10 + 20;
      this.y = Math.cos(this.t/30)*10 + 20;
      this.ele.setAttribute('x', this.x);
      this.ele.setAttribute('y', this.y);
      console.log('x:y = ' + this.x + ':' + this.y);
      console.log('dx:dy = ' + this.dx + ':' + this.dy);
    }
  }
  var item = new Item();


  if(document.addEventListener){
    console.log(item);
    item.ele.addEventListener('click', item.handler, false);

    setInterval(function(item){
      item.move();
    }, 20, item);

  }

})();

svg{
  width:400px;
  height:400px;
}

ページのソースを表示 : Ctrl+U , DevTools : F12

view-source:https://hi0a.com/demo/-svg/svg-js-setAttribute/