No matter how much you plan, or how much foresight you have, it's inevitable: At some point you'll get an error. Errors can occur when a programmer tries to use a method with an object that doesn't support it, or tries to use an object variable that has not been initialized, or simply makes a typing mistake. There are literally hundreds of errors that can occur in any given program and often more than one way to interpret the messages that the errors generate. Learning where and how an error occurred takes quite a bit of skill and patience. Luckily, most modern Web browsers have built-in debuggers to help you find and fix errors in code. This chapter will discuss the basic makeup of error messages and present many steps you can go through in order to solve the errors you inevitably encounter.
Another way to locate the errors on a Web page—especially if it isn't your own—is to view the source of the Web page itself. To do so in Netscape, open the View menu and select Page Source. This will bring up a separate window containing the textual source of the current page as shown in Figure 13.3.