Best PracticesFollowing the Development, Testing, and Production Model

One of the most commonand dangerousmistakes I see novice web developers engage in is the editing of web pages or applications on their production servers. Usually, these changes are made after an urgent request, and when the change or changes seem relatively harmless. The danger of doing this, however, is magnified when you start making live changes to complex applications such as those that are database-driven. A single slip of the keyboard in the code view and you can delete a single character such as a % in VBScript or a ! in JavaScript. This missing character can either break the application or change its entire functionality. For example, a function that is supposed to check for form fields that are not empty with the != "" command might now check for fields that are empty with the ="" command.

Because of the possibility of making these simple mistakes, it is important to create a development machine where you can test your changes prior to migrating them to your production server. Each change that is made on the development machine shouldn't just be tested to see whether the page loads, but also tested to ensure that the entire page functions as expected. Only after you are positive that your changes are valid should you move it into production and even then, it's a good idea not to replace the previous file, but rename it and archive it in case you need to step back a version.

This process might seem tedious and time-consuming, but I speak from experience in saying that it can ensure that the changes you make do not adversely affect your web application.