Noticed weired javascript appended in email field, during comment moderation

I have noticed a very weired problem. While moderating a comment of one of my visitor through dashboard, I noticed some javascript code after the email address of the comment author. The code is as follows:

/* <![CDATA[ */(function(){try{var s,a,i,j,r,c,l=document.getElementById("__cf_email__");a=l.className;if(a){s='';r=parseInt(a.substr(0,2),16);for(j=2;a.length-j;j+=2){c=parseInt(a.substr(j,2),16)^r;s+=String.fromCharCode(c);}s=document.createTextNode(s);l.parentNode.replaceChild(s,l);}}catch(e){}})();/* ]]> */

I got suspicious but upon checking up all the other comments of various visitors I found the same code appended just after the end of the email address. Can someone put some light about this behavior? I am really confused…