function count(text_area, max) {
    if (text_area.value.length >= max) {
        text_area.value = text_area.value.substring(0, max);
    }
}

function blockNonNumbers(obj, e, allowDecimal, allowNegative) {
    var key;
    var isCtrl = false;
    var keychar;
    var reg;

    if (window.event) {
        key = e.keyCode;
        isCtrl = window.event.ctrlKey
    }
    else if (e.which) {
        key = e.which;
        isCtrl = e.ctrlKey;
    }

    if (isNaN(key)) return true;

    keychar = String.fromCharCode(key);

    // check for backspace or delete, or if Ctrl was pressed
    if (key == 8 || isCtrl) {
        return true;
    }

    reg = /\d/;
    var isFirstN = allowNegative ? keychar == '-' && obj.value.indexOf('-') == -1 : false;
    var isFirstD = allowDecimal ? keychar == '.' && obj.value.indexOf('.') == -1 : false;
    //alert(isFirstN || isFirstD || reg.test(keychar));
    return isFirstN || isFirstD || reg.test(keychar);
}