DotNetOutputToConsole 1.1.0

DotNetOutputToConsole

A secure ASP.NET Framework (4.8 / 4.8.1) helper library that writes logs, variables, and exceptions directly to the browser console — perfect for UAT and DEV environments.

What's New in v1.0.0

Features

• Write messages, variables, and errors to the browser console (console.info, console.log, console.error)
• Automatically logs unhandled exceptions globally
• Works with any ASP.NET Web Forms or MVC project
• Simple global toggle via web.config
• XSS-safe using System.Web.Helpers.Json.Encode to sanitize all outputs
• Zero third-party dependencies
• Includes unit tests and a demo web app
• Fully compatible with .NET Framework 4.8 to 4.8.1

What's New in v1.1.0

• Removed dependency on System.Web.Helpers (Json.Encode() no longer required)
• Now uses HttpUtility.JavaScriptStringEncode (safe, built-in, no external packages)
• Improved XSS safety logic
• Cleaned references to reduce DLL size
• Updated module to correctly handle missing AppSettings
• Assembly version sync: 1.1.0.0
• NuGet package version: 1.1.0

Features

• Write messages, variables, and errors to the browser console (console.info, console.log, console.error)
• Automatically logs unhandled exceptions globally
• Works with any ASP.NET Web Forms or MVC project
• Simple global toggle via web.config
• No third-party dependencies
• Includes unit tests and demo web app
• Fully compatible with .NET Framework 4.8 to 4.8.1

Installation

Install from NuGet using the Package Manager Console:

Install-Package DotNetOutputToConsole

Purpose

When deploying ASP.NET applications to UAT or DEV environments, developers often need to inspect runtime values or exceptions directly in the browser console. This library provides a safe, fast, invisible way to do that without altering page UI or showing alert popups.

Example:

DotNetOutputToConsoleLogger.LogVariable("SessionId", Session.SessionID);
DotNetOutputToConsoleLogger.LogError("Missing input data");

Console output:

LOG: SessionId: 1a2b3c4d
ERROR: Missing input data

Architecture Overview

Configuration

Add the following to your Web.config:

<configuration>
  <appSettings>
    <add key="EnableOutputToConsole" value="true" />
  </appSettings>

  <system.webServer>
    <modules>
      <add name="DotNetOutputToConsoleHttpModule"
           type="DotNetOutputToConsole.DotNetOutputToConsoleHttpModule" />
    </modules>
  </system.webServer>
</configuration>

Set "EnableOutputToConsole" to "true" in UAT or DEV. Set to "false" in production.

Usage Examples

Log Information

DotNetOutputToConsoleLogger.LogInfo("Page load completed");

Output:

INFO: Page load completed

Log Variables

DotNetOutputToConsoleLogger.LogVariable("Username", user.Name);

Output:

LOG: Username: JohnDoe

Log Exceptions

try
{
    throw new Exception("Simulated failure");
}
catch (Exception ex)
{
    DotNetOutputToConsoleLogger.LogError(ex.Message);
}

Output:

ERROR: Simulated failure

Automatic Error Logging (Unhandled Exceptions)

protected void Page_Load(object sender, EventArgs e)
{
    throw new Exception("Unhandled page error!");
}

Output:

ERROR: Unhandled Exception: Unhandled page error!

Class Overview

DotNetOutputToConsoleLogger.cs

public static class DotNetOutputToConsoleLogger
{
    public static void LogInfo(string message);
    public static void LogVariable(string name, object value);
    public static void LogError(string message);
}

DotNetOutputToConsoleHttpModule.cs

public class DotNetOutputToConsoleHttpModule : IHttpModule
{
    public void Init(HttpApplication context)
    {
        context.Error += (sender, e) =>
        {
            var ex = HttpContext.Current?.Server.GetLastError();
            if (ex != null)
                DotNetOutputToConsoleLogger.LogError($"Unhandled Exception: {ex.Message}");
        };
    }
}

Security

Unit Testing

Test Framework Installation

Install-Package NUnit
Install-Package NUnit3TestAdapter
Install-Package Microsoft.NET.Test.Sdk

Example Test

[Test]
public void LogInfo_ShouldNotThrow()
{
    Assert.DoesNotThrow(() => DotNetOutputToConsoleLogger.LogInfo("info"));
}

Run Tests

Visual Studio 2022 → Test Explorer → Run All Tests
or CLI:

dotnet test

Project Structure

DotNetOutputToConsole/
├── src/
│   └── DotNetOutputToConsole/
│       ├── DotNetOutputToConsoleLogger.cs
│       ├── DotNetOutputToConsoleHttpModule.cs
│       ├── Properties/
│       │   └── AssemblyInfo.cs
│       ├── README.md
│       └── LICENSE
├── demo/
│   └── DotNetOutputToConsole.DemoWeb/
│       ├── Default.aspx
│       ├── Default.aspx.cs
│       └── Web.config
└── tests/
    └── DotNetOutputToConsole.Tests/
        └── DotNetOutputToConsoleLoggerTests.cs

How It Works

1. The logger injects <script> tags into the HTTP response.
2. Messages are encoded using Json.Encode() to prevent script injection.
3. Output executes inside the browser console.
4. View results using Developer Tools → Console.

Author

Created by: livedcode
GitHub: https://github.com/livedcode
NuGet: https://www.nuget.org/profiles/livedcode

License

MIT License © 2025 livedcode