Note: After saving, you have to bypass your browser's cache to see the changes. Google Chrome, Firefox, Microsoft Edge and Safari: Hold down the ⇧ Shift key and click the Reload toolbar button. For details and instructions about other browsers, see Wikipedia:Bypass your cache.
String.prototype.trim = function(){return this.replace(/^\s*|\s*$/g,"")};
 
if (typeof usersignature == 'undefined') usersignature = ' --\~\~\~\~\n';
 
if (typeof regpages == 'undefined') { // list of all none talk pages
var regpages = [
':Village pump',
':Articles for deletion',
':Requests for ',
':Reference desk',
':Deletion review',
':Templates for deletion',
'.*noticeboard.*',
':checkuser',
':arbitration',
':feedback',
':page protection',
'mediation)',
':Bot requests',
':Help desk',
':Editor review',
':Adminship survey',
':Cleanup',
':Miscellany for deletion',
':New contributors\' help page',
':Media copyright questions'
];
} 
 
// regarded pages type encoded
if (wgCanonicalNamespace.match(/talk$/i)) var regpages = "";
for (p in regpages) if (wgPageName.indexOf(regpages[p]) != -1){regpages=false; break}
 
if (!regpages) 
addOnloadHook(function(){
if (!(window.editform = document.forms['editform'])) return;
// Add a new checkbox to the Wiki editOptions.
sigBox = document.createElement("input");
sigBox.setAttribute('type','checkbox');
sigBox.setAttribute('name','wpSigning');
sigBox.setAttribute('id','wpSigning');
sigBox.setAttribute('checked','checked');
sigBox.defaultChecked=true;
neuB = document.createElement("label");
neuB.appendChild(sigBox);
neuB.appendChild(document.createTextNode("Sign"));
neuB.setAttribute('for','wpSigning');
neuB.setAttribute('title','Sign this edit automatic.');
 
function setSigBox() { // switch enable box
if (editform.wpMinoredit.checked) sigBox.setAttribute('disabled','disabled');
else sigBox.removeAttribute('disabled');
};
 
var txtarea=editform.elements['wpTextbox1'];
var txtOld=txtarea.value.trim();
// txtOld_l=txtOld.length
var txtOldEnd=txtOld.slice(-24);
var sig = /~{3}/g;
 
if (!tNode){
//editform.insertBefore(neuB, editform.elements['wpWatchthis']); // maybe FIXME: raised an NS_DOM_ERR!
var tNode = editform.elements['wpMinoredit'].parentNode;  // DOM workaround!?
tNode.divs = tNode.getElementsByTagName("DIV");
tNode.divs = tNode.divs.item(tNode.divs.length-1); // last div
tNode.insertBefore(neuB, tNode.divs);
setSigBox();
}
 
function doSign(event){
if(editform.onsubmit==''){ // only once!
removeEvent(editform.wpSave,"click",doSign);
removeEvent(editform.wpPreview,"click",doSign);
}
if(editform.onsubmit=='') removeEvent(editform.wpSave,"click",doSign); // only once!
if(editform.wpMinoredit.checked || !sigBox.checked) return;
txtarea.focus();
var cOld = txtOld.match(/<nowiki>.*?~{3}.*?<\/nowiki>/g); // exception for nowiki
if (cOld) cOld = cOld.length;
cNew = txtarea.value.match(sig); if (cNew) cNew = cNew.length;
if (cNew > cOld){ // if there are a sign, check for true
var cNew2 = txtarea.value.match(/\{\{subst\:unsig.*?~{3}\}\}/); // exception for Template:unsigned
cNew -= (cNew2)?cNew2.length:0;
}
if(cNew <= cOld){ // if nothing then search a set position
txt=txtarea.value.trim();
txtEnd=txt.slice(-24);
if(txtOldEnd!=txtEnd) return txtarea.value = txt + usersignature;  // aut. underwrite
else { // post between
pos = getCaretPos(txtarea);
pos = txt.indexOf('\n', pos); // go to the post-end
txtEnds = txt.substr(pos,24).replace(/(^\s*)/,""); // after
txtpEnds = txt.slice(pos-18,pos); // before
oldp = txtOld.indexOf(txtEnds);
if(oldp!=-1 && oldp < pos - 3 && txtOld.indexOf(txtpEnds+RegExp.$1+txtEnds)==-1) // if some added
return txtarea.value = txt.slice(0,pos).trim() + usersignature + txt.slice(pos+1);
}
// FIXME: then the edit-end is not found!?
}
else if(!sig.test(txtOld) || cOld < cNew) return;
if (event) event=(window.Event)? event.target: event.srcElement;
if (event.name == 'wpPreview') return; // not for preview
return editform.onsubmit=new Function("editform.onsubmit='';"
+"return confirm('No signing was found. Continue anyway?')"); //warn if saving without signature
};
addEvent(editform.wpSave,"click", doSign);
addEvent(editform.wpPreview,"click", doSign);
addEvent(editform.wpMinoredit,"click", setSigBox);
});
 
function getCaretPos(txtObj){
if (txtObj.setSelectionRange) return txtObj.selectionStart; // NS like
else if(!document.selection) return 0;  // not IE like
var c="\001", pos=0;
var range=document.selection.createRange();
var txt=range.text, dul=range.duplicate();
dul.moveToElementText(txtObj);
range.text=txt+c;
pos=(dul.text.indexOf(c));
range.moveStart('character',-1);
range.text="";
return pos;
};
 
/* add/removeEvent Original idea by John Resig
Tweaked by Scott Andrew LePera, Dean Edwards and Peter-Paul Koch
Fixed for IE by Tino Zijdel (crisp) @date 2005-10 */
function addEvent(obj,type,fn){if(obj.addEventListener){obj.addEventListener(type,fn,false)}else if(obj.attachEvent){var eProp=type+fn;obj["e"+eProp]=fn;obj[eProp]=function(){obj["e"+eProp](window.event)};obj.attachEvent("on"+type,obj[eProp])}else{obj['on'+type]=fn}};
function removeEvent(obj,type,fn){if(obj.removeEventListener){obj.removeEventListener(type,fn,false)}else if(obj.detachEvent){var eProp=type+fn;obj.detachEvent("on"+type,obj[eProp]);obj['e'+eProp]=null;obj[eProp]=null}else{obj['on'+type]=null}};
 
// *** end *** </nowiki></pre>