Can't spambots decode encoded email addresses?

I implemented an email encoder for my WordPress site, the plugin will convert an address to something like this

%6f%73%6f%72%69%6f%40%68%65%63%2e%63%6f

and decode it via a piece of JavaScript code

<span id="eeb-638789-855127"></span>
<script type="text/javascript">
document.getElementById("eeb-638789-855127").innerHTML = eval(decodeURIComponent("%6f%73%6f%72%69%6f%40%68%65%63%2e%63%6f"))
</script>

I was wondering why this is working to prevent spambots from harvesting emails. Can't spambots decode that encoded address to get the original one?