function isControlKey(key) {
    if ((key==null) || (key==0) || (key==8) || (key==9) ||
        (key==13) || (key==16) || (key==25) || (key==27) || (key==63272))
        return true;
    else
        return false;
}

function numbersonly(e) {
    var key;
    var keychar;

    if (window.event)
       key = window.event.keyCode;
    else if (e)
       key = e.which;
    else
       return true;
    keychar = String.fromCharCode(key);

// control keys
    if (isControlKey(key))
       return true;

// numbers
    else if ((("0123456789").indexOf(keychar) > -1))
       return true;

    else
       return false;
}

    function lettersonly(e) {
        var key;
        var keychar;
        if (window.event) key = window.event.keyCode;
        else if (e) key = e.which;
        else return true;

        keychar = String.fromCharCode(key);
//      control keys
        if (isControlKey(key))
            return true;
//      letters + space
		// Khanh Start modify code for PR200709 Spanish website - 
        // add accent: í and Í for spanish language to use in payment agreement "Sí"
        else if ((("abcdefghiíjklmnopqrstuvwxyzABCDEFGHIÍJKLMNOPQRSTUVWXYZ'- ").indexOf(keychar) > -1))
        // Khanh ended modify code for PR200709 Spanish website
           return true;
        else
           return false;
    }
function handleEnter() {
	if (window.event && window.event.keyCode == 13) {
		document.getElementById("buttonContinue").click();
		return false;
	}
	return true;
}