kura.js

(function() {
var body=document.getElementsByTagName('body').item(0);
var goLeft = 1;
var ih = body.innerHTML;
ih = '<img src="https://s-media-cache-ak0.pinimg.com/originals/7a/3d/8d/7a3d8d337b1e0f257ba2eb75a6bf355e.gif" class="ux-hen" style="visibility: hidden">' + ih;
body.innerHTML = ih;
var kura = document.getElementsByClassName('ux-hen').item(0);
kura.style.position='fixed';
kura.style.width='100px';
kura.style.bottom='20px';
kura.style.zIndex=10000000;

kura.style.right='20px';
kura.style.visibility='visible';
kura.style.transition='right 3s, width 2s';



function move() {
    var next =(Math.random()*100).toFixed();
    if(Math.random()>0.5) {
        if(goLeft > 0) {
          kura.style.transform='scale(-1,1)';
          goLeft = -1;
        } else {
          kura.style.transform='scale(1,1)';
          goLeft = 1;
        }
    }
    
    var newPos = (Number.parseInt(kura.style.right) + (goLeft * next));
    if (newPos < 20) {
        newPos=20;
    }
    console.log(newPos + "px");
    kura.style.right=newPos + "px";
    console.log(kura.style.right);
}

setInterval(move, 3000);
})()