JavaScript is also pretty speedy. Like most scripting languages, it’s interpreted (as opposed to being compiled). When you program using a compiled language, such as C++, you must always reformat, or compile, your code file before you can run it. This interim step can take anywhere from a few seconds to several minutes or more.
The beauty of an interpreted language like JavaScript, on the other hand, is that when you make changes to your code — in this case, to your JavaScript script — you can test those changes immediately; you don’t have to compile the script file first. Skipping the compile step saves a great deal of time during the debugging stage of Web page development.
Another great thing about using an interpreted language like JavaScript is that testing an interpreted script isn’t an all-or-nothing proposition, the way it is with a compiled language. For example, if line 10 of a 20-line script contains a syntax error, the first half of your script may still run, and you may still get feedback immediately. The same error in a compiled program may prevent the program from running at all.
The downside of an interpreted language is that testing is on the honor system. Because there’s no compiler to nag you, you might be tempted to leave your testing to the last minute or — worse yet — skip it altogether. However, remember that whether the Web site you create is for business or pleasure, it’s a reflection on you, and testing is essential if you want to look your very best to potential customers, associates, and friends. (A few years ago, visitors to your site might have overlooked a buggy script or two, but frankly, Web site standards are much higher these days.)
Everybody’s doing it! (Okay, almost everybody!)
Two generally available Web browsers currently support JavaScript: Microsoft’s Internet Explorer and Netscape/AOL’s Navigator. (Beginning with version 4.0, Navigator became synonymous with Communicator, even though technically Netscape Communicator includes more components than just the Navigator Web browser.) Between them, these two browsers have virtually sewn up the browser market; almost everyone who surfs the Web is using one or the other — and thus has the ability to view and create JavaScript-enabled Web pages.