Untitled

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>

<!DOCTYPE html>


<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title>Интерпритатор</title>


</head>
<body>


    <form id="form1" runat="server">

    <div>
        <h1>Интерпритатор</h1>


    </div>
        <p>
            Ввод</p>

        <asp:TextBox  ID="TextBox1" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Старт"  Enabled="false"/>
        <p>
            Вывод</p>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <asp:Button ID="Button2" runat="server" Text="Отмена" OnClick="Button2_Click" />
        <script lang =" javascript" type ="text/javascript" >
        var input = document.getElementById('TextBox1');
        var button = document.getElementById('Button1');

        input.addEventListener('input', function f() { button.disabled = (input.value === ''); })
        </script>
    </form>
</body>

</html>