If using function onclick DIV and then want to disable click it again you can use this :
for (var i=0;i<document.getElementsByClassName('ads').length;i++){
document.getElementsByClassName('ads')[i].onclick = false;
}
Example :
HTML
<div id='mybutton'>Click Me</div>
Javascript
document.getElementById('mybutton').onclick = function () {
alert('You clicked');
this.onclick = false;
}