/*==========================================================================# 
# * Function for adding a Filter to an Input Field                          # 
# * @param  : [filterType  ] Type of filter 0=>Alpha, 1=>Num, 2=>AlphaNum   # 
# * @param  : [evt         ] The Event Object                               # 
# * @param  : [allowDecimal] To allow Decimal Point set this to true        # 
# * @param  : [allowCustom ] Custom Characters that are to be allowed       # 
#==========================================================================*/ 
function filterInput(filterType, evt, allowDecimal, allowCustom){ 
    var keyCode, Char, inputField, filter = ''; 
    var alpha = 'abcçdefgğhıijklmnoöpqrsştuüvwxyzABCÇDEFGĞHIİJKLMNOÖPQRSŞTUÜVWXYZ'; 
    var num   = '0123456789'; 
    // Get the Key Code of the Key pressed if possible else - allow 
    if(window.event){ 
        keyCode = window.event.keyCode;
        evt = window.event; 
    }else if (evt)keyCode = evt.which; 
    else return true; 
    // Setup the allowed Character Set 
    if(filterType == 0) filter = alpha; 
	
    else if(filterType == 1) filter = num; 
	
    else if(filterType == 2) filter = alpha + num; 
	
    if(allowCustom)filter += allowCustom; 
	
    if(filter == '')return true; 
    // Get the Element that triggered the Event 
    inputField = evt.srcElement ? evt.srcElement : evt.target || evt.currentTarget; 
    // If the Key Pressed is a CTRL key like Esc, Enter etc - allow 
    if((keyCode==null) || (keyCode==0) || (keyCode==8) || (keyCode==9) || (keyCode==13) || (keyCode==27) )return true; 
    // Get the Pressed Character 
    Char = String.fromCharCode(keyCode); 
    // If the Character is a number - allow 
    if((filter.indexOf(Char) > -1)) return true; 
    // Else if Decimal Point is allowed and the Character is '.' - allow 
    else if(filterType == 1 && allowDecimal && (Char == '.') && inputField.value.indexOf('.') == -1)return true; 
    else return false; 
}