<script type="text/javascript">
var options = {
    htmlcopytxt:  ' Источник: <a href="' + window.location.href + '">' + window.location.href + '</a><br />',
    minlen:       25,
    addcopyfirst: false
};
    
var copy_sp = document.createElement('span');

copy_sp.id        = 'ctrlcopy';
copy_sp.innerHTML = options.htmlcopytxt;

function selectionMore() {
    if(window.getSelection) {    //good times
        var slcted = window.getSelection();
        var seltxt = slcted.toString();
        
        if(!seltxt||seltxt.length < options.minlen) return;
        
        var nslct = slcted.getRangeAt(0);
        seltxt    = nslct.cloneRange();
        seltxt.collapse(options.addcopyfirst);
        seltxt.insertNode(copy_sp);
        
        if (!options.addcopyfirst) nslct.setEndAfter(copy_sp);
        
        slcted.removeAllRanges();
        slcted.addRange(nslct);
    } else if(document.selection) {    //bad times
        var slcted = document.selection;
        var nslct  = slcted.createRange();
        var seltxt = nslct.text;
        
        if (!seltxt||seltxt.length<options.minlen) return;
        
        seltxt = nslct.duplicate();
        
        seltxt.collapse(options.addcopyfirst);
        seltxt.pasteHTML(copy_sp.outerHTML);
        
        if(!options.addcopyfirst) {nslct.setEndPoint("EndToEnd",seltxt); nslct.select();}
    }
}

document.addEventListener("mouseup", selectionMore);
document.addEventListener("keyup", selectionMore);
</script>