iterating through node list
HTML
<p class="blue">
Lorem ipsum dolor sit amet, consectetur adipisicing elit.
</p>
<p class = "blue">
Lorem ipsum dolor sit amet, consectetur adipisicing elit.
</p>
CSS
.blue{
background: blue;
}
.orange{
background:orange;
}
JavaScript
var access = document.getElementsByClassName("blue");
for(var i = access.length - 1; i > -1; i--){
access[i].className = "orange";
}