Js decimal verification function code (based on regularity)

function OnKeyPressValidate(obj, event, len) {
var e = || event;
var key = ? : ;
var selectedText = "";
if () {
var st = ;
var ed = ;
selectedText = (st, ed);
} else if () {
selectedText = ().text;
}
if (selectedText != null && selectedText != "") {
return true;
}
var dot = (".");
len = (typeof (len) == "undefined") ? 2 : len;
if () {
}
else {
if (key == 8 || key == 9 || key == 46 || (key >= 37 && key <= 40))//for Firefox
return true;
}
if (key <= 57 && key >= 48) {
if (dot == -1)
return true;
else if ( <= dot + len)
return true;
} else if ((key == 46) && dot == -1) {
return true;
}
return false;
}