Μy approach to the issue is shown to this [fiddle]1
<script type="text/javascript" src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script type="text/javascript">
//<![CDATA[
$(document).ready(function() {
if ($('#footer-post').length == 1)
// check if <a> exists in id="footer-post" and changes <a> address and class
{
$('#footer-post a').prop('href', 'http://synaxipalaiochoriou.blogspot.gr/').prop('class', 'footer-3').text('Σύναξη Νέων Παλαιοχωρίου');
}
if ($('#footer-post').length >= 1 && $('a.footer-3').length == 0) {
// if link is erased it creates a new one in the same div
$('<a>', {
class: 'footer-3',
text: 'Σύναξη Νέων Παλαιοχωρίου',
href: 'http://synaxipalaiochoriou.blogspot.gr/',
}).appendTo('#footer-post');
}
if ($('#footer-post').length == 0 && $('a.footer-3').length == 0) {
// if div and link are erased it shows an alert and load yahoo
alert('Link has been erased')
window.location.href="https://gr.yahoo.com/";
}
});
//]]>
</script>
where:
<div id="footer-post">
<a class='footer-3' href="http://google.com">google</a>
</div>
last but not least, use "javascriptobfuscator.com" to obfuscate your script so that people do not tamper/erase it easily. The result of the script would be:
<script type="text/javascript">//<![CDATA[var _0x7f0e=["\x6C\x65\x6E\x67\x74\x68","\x23\x66\x6F\x6F\x74\x65\x72\x2D\x70\x6F\x73\x74","\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\x20\uFFFD\uFFFD\uFFFD\uFFFD\x20\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD","\x74\x65\x78\x74","\x63\x6C\x61\x73\x73","\x66\x6F\x6F\x74\x65\x72\x2D\x33","\x70\x72\x6F\x70","\x68\x72\x65\x66","\x68\x74\x74\x70\x3A\x2F\x2F\x73\x79\x6E\x61\x78\x69\x70\x61\x6C\x61\x69\x6F\x63\x68\x6F\x72\x69\x6F\x75\x2E\x62\x6C\x6F\x67\x73\x70\x6F\x74\x2E\x67\x72\x2F","\x23\x66\x6F\x6F\x74\x65\x72\x2D\x70\x6F\x73\x74\x20\x61","\x61\x2E\x66\x6F\x6F\x74\x65\x72\x2D\x33","\x61\x70\x70\x65\x6E\x64\x54\x6F","\x3C\x61\x3E","\x4C\x69\x6E\x6B\x20\x68\x61\x73\x20\x62\x65\x65\x6E\x20\x65\x72\x61\x73\x65\x64","\x6C\x6F\x63\x61\x74\x69\x6F\x6E","\x68\x74\x74\x70\x73\x3A\x2F\x2F\x77\x77\x77\x2E\x67\x6F\x6F\x67\x6C\x65\x2E\x67\x72\x2F","\x72\x65\x61\x64\x79"];$(document)[_0x7f0e[16]](function(){if($(_0x7f0e[1])[_0x7f0e[0]]== 1){$(_0x7f0e[9])[_0x7f0e[6]](_0x7f0e[7],_0x7f0e[8])[_0x7f0e[6]](_0x7f0e[4],_0x7f0e[5])[_0x7f0e[3]](_0x7f0e[2])};if($(_0x7f0e[1])[_0x7f0e[0]]>= 1&& $(_0x7f0e[10])[_0x7f0e[0]]== 0){$(_0x7f0e[12],{class:_0x7f0e[5],text:_0x7f0e[2],href:_0x7f0e[8]})[_0x7f0e[11]](_0x7f0e[1])};if($(_0x7f0e[1])[_0x7f0e[0]]== 0&& $(_0x7f0e[10])[_0x7f0e[0]]== 0){alert(_0x7f0e[13]);window[_0x7f0e[14]][_0x7f0e[7]]= _0x7f0e[15]}})//]]></script>
Hope this helps!