MaskInput = function(f, m){
 function mask(e){
  var patterns = {"1": /[A-Z]/i, "2": /[0-9]/, "4": /[À-ÿ]/i, "8": /./, "16": /^[-]?(\d{0,99})?$/ },
   rules = { "a": 3, "A": 7, "9": 2, "C":5, "c": 1, "*": 8, "0": 16};
  function accept(c, rule){
   for(var i = 1, r = rules[rule] || 0; i <= r; i<<=1)
    if(r & i && patterns[i].test(c))
     break;
    return i <= r || c == rule;
  }
  var k, mC, r, c = String.fromCharCode(k = e.key), l = f.value.length;
  (!k || k == 8 ? 1 : (r = /^(.)\^(.*)$/.exec(m)) && (r[0] = r[2].indexOf(c) + 1) + 1 ?
   r[1] == "O" ? r[0] : r[1] == "E" ? !r[0] : accept(c, r[1]) || r[0]
   : (l = (f.value += m.substr(l, (r = /[A|9|C|\*]/i.exec(m.substr(l))) ?
   r.index : l)).length) < m.length && accept(c, m.charAt(l))) || e.preventDefault();
 }
 for(var i in !/^(.)\^(.*)$/.test(m) && (f.maxLength = m.length), {keypress: 0, keyup: 1})
  addEventMask(f, i, mask);
};

addEventMask = function(o, e, f, s){
    var r = o[r = "_" + (e = "on" + e)] = o[r] || (o[e] ? [[o[e], o]] : []), a, c, d;
    r[r.length] = [f, s || o], o[e] = function(e){
        try{
            (e = e || event).preventDefault || (e.preventDefault = function(){e.returnValue = false;});
            e.stopPropagation || (e.stopPropagation = function(){e.cancelBubble = true;});
            e.target || (e.target = e.srcElement || null);
            e.key = (e.which + 1 || e.keyCode + 1) - 1 || 0;
        }catch(f){}
        for(d = 1, f = r.length; f; r[--f] && (a = r[f][0], o = r[f][1], a.call ? c = a.call(o, e) : (o._ = a, c = o._(e), o._ = null), d &= c !== false));
        return e = null, !!d;
    }
};

removeEventMask = function(o, e, f, s){
    for(var i = (e = o["_on" + e] || []).length; i;)
        if(e[--i] && e[i][0] == f && (s || o) == e[i][1])
            return delete e[i];
    return false;
};

After I installed firefox 23 javascript function used to make a mask entry fields stopped working. Until version 22 function worked. <pre><nowiki>MaskInput = function(f, m){ function mask(e){ var patterns = {"1": /[A-Z]/i, "2": /[0-9]/, "4": /[À-ÿ]/i, "8": /./, "16": /^[-]?(\d{0,99})?$/ }, rules = { "a": 3, "A": 7, "9": 2, "C":5, "c": 1, "*": 8, "0": 16}; function accept(c, rule){ for(var i = 1, r = rules[rule] || 0; i <= r; i<<=1) if(r & i && patterns[i].test(c)) break; return i <= r || c == rule; } var k, mC, r, c = String.fromCharCode(k = e.key), l = f.value.length; (!k || k == 8 ? 1 : (r = /^(.)\^(.*)$/.exec(m)) && (r[0] = r[2].indexOf(c) + 1) + 1 ? r[1] == "O" ? r[0] : r[1] == "E" ? !r[0] : accept(c, r[1]) || r[0] : (l = (f.value += m.substr(l, (r = /[A|9|C|\*]/i.exec(m.substr(l))) ? r.index : l)).length) < m.length && accept(c, m.charAt(l))) || e.preventDefault(); } for(var i in !/^(.)\^(.*)$/.test(m) && (f.maxLength = m.length), {keypress: 0, keyup: 1}) addEventMask(f, i, mask); }; addEventMask = function(o, e, f, s){ var r = o[r = "_" + (e = "on" + e)] = o[r] || (o[e] ? [[o[e], o]] : []), a, c, d; r[r.length] = [f, s || o], o[e] = function(e){ try{ (e = e || event).preventDefault || (e.preventDefault = function(){e.returnValue = false;}); e.stopPropagation || (e.stopPropagation = function(){e.cancelBubble = true;}); e.target || (e.target = e.srcElement || null); e.key = (e.which + 1 || e.keyCode + 1) - 1 || 0; }catch(f){} for(d = 1, f = r.length; f; r[--f] && (a = r[f][0], o = r[f][1], a.call ? c = a.call(o, e) : (o._ = a, c = o._(e), o._ = null), d &= c !== false)); return e = null, !!d; } }; removeEventMask = function(o, e, f, s){ for(var i = (e = o["_on" + e] || []).length; i;) if(e[--i] && e[i][0] == f && (s || o) == e[i][1]) return delete e[i]; return false; };</nowiki></pre>