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A.2 Editors and IDEs

Code-editing tools vary a great deal in complexity, from the simple Notepad to complex IDEs that model the code objects in a variety of ways as you type. JavaScript, HTML, and CSS aren’t as well supported as enterprise-class languages such as C#, Visual Basic, and Java, but there’s still quite a wide range of functionality from which to choose. Let’s run through the types of features that we might look for before we consider the products available today.

A.2.1 What to look for in a code editor

Code editors can do many things, arguably too many. A lot of it comes down to individual tastes. Some developers prefer a simple tool that processes text; others like the visual aids and cues of a full-blown IDE.

When it comes to supporting Ajax code, in the form of HTML, CSS, and JavaScript, there are a number of ways in which the editor can help us. Many of these may seem like overkill for the web content of a classic web app, but as the codebase of an Ajax application is typically much larger and more structured, support for that structuring becomes more critical. Here’s a quick rundown of useful features to look for.

Multiple file support

This is a very basic requirement but worth noting anyway. Ajax projects will typically entail a large number of files, and an editor that cannot manage multiple files or buffers (such as Windows Notepad) will quickly become annoying. Nearly all coding editors support multiple files through tabbed panels, a selector panel, or something similar.

Syntax highlighting

This is a fairly basic feature nowadays and one that most programmer’s editors will support. Syntax highlighting simply colors, italicizes, or otherwise marks language keywords, symbols, quoted strings, and code comments, making it easier to read a sequence of code.

Most editors support syntax coloring for a range of languages, often with pluggable syntax definition files. The key issue for Ajax programming is that a variety of languages are typically used. There are HTML, CSS, XML, and JavaScript on the client side, all of which can benefit from syntax highlighting, and some or all of Java, C#, VB, and the more complex ASP, PHP, and JSP, in which blocks of HTML and code alternate with one another. Not all syntax-aware editors support the full range of languages in use in an Ajax project.

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Higher-level code support

Coloring in the code provides useful visual cues, but some editors go beyond this to model the code at a higher level of function, methods, and object declarations. This higher-level understanding of a codebase opens up a broader range of tools such as outliners that summarize a file’s contents, navigational aids such as maps of object hierarchies, and the ability to search for uses of a specific property or invocations of a method or function. Tools of this type become invaluable as a codebase matures.

Project-level support tools

Taking another step up from modeling individual object definitions, some IDEs will also manage a codebase as an integrated project, recognizing linkages between the various components and resources that lead to a deployed product. In an IDE for a compiled language, a key benefit of this is the ability to build the entire project into executable form, but this isn’t a concern for Ajax, in which all clientside resources are deployed in their human-readable form. Nonetheless, this capability may be useful when working with server-side code.

Further, project-level support may provide the ability to deploy a project to a web server, even to manage the web server itself, either by controlling an external server through RPC calls or by embedding a simple server into the IDE. A tool that supports the codebase at the project level can release the developer from maintaining a build-and-deploy system.

Version control integration

Version control is a necessity in larger projects and good practice in a project of any size. Version-control systems themselves generally work on text and binary files without understanding their higher-level semantics, so there is little to say about them that is specific to Ajax, but integrating version control into your toolset can be a great help.

Mixed-language development: client and server integration

As we noted earlier, many Ajax projects will require a server-side component in addition to the many web browser technologies being employed. Server-side JavaScript is possible but not fashionable, and the Ajax developer will usually make use of different languages on the server side and the client side. It is possible to use completely different tools for server and client coding, but some tasks will involve rapidly switching between the tiers, and an editor that can support the full range of languages can be a distinct advantage.

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Those, then, are our main criteria for choosing a code editor, whether it be a plain text editor or an IDE. In the next section, we’ll have a look at some of the available tools at the time this book was written.

Two-way visual designers

Many web-design tools provide visual WYSIWYG designers for web pages. These can be useful for prototyping, although they are often poorly adapted to Ajax’s more dynamic approach to rearranging the user interface through DOM manipulation. Most visual editors will also allow the programmer to switch to a textbased view of the HTML. When you’re using this kind of tool with Ajax, it is important that the visual editor preserve elements that it does not understand, such as comments and custom tag types and attributes, particularly as the latter may be used by the JavaScript code that rearranges the DOM tree.

A.2.2 Current offerings

A variety of text editors and IDEs offer some support for Ajax technologies. We’ll start by looking at the programmer’s editors and move on from there to the more complex IDEs.

Text editors

Depending on your operating system, a wide range of open source, freeware, and shareware text editors is available these days, such as shareware tools TextPad, Notepad2, EditPlus, the UNIX veterans Vim and Emacs, and the extensible cross-platform jEdit, whose plug-in system enables some IDE-like functionality. Figure A.1 shows a few common text editors in JavaScript mode.

TextPad provides a staggeringly diverse base of user-contributed syntax definition files, including several for CSS, JavaScript, XML, and HTML, and for most popular server-side languages. There is minimal support for running userdefined commands such as compilers against the current file. TextPad runs on Microsoft Windows only. NotePad2 and EditPlus fill similar niches.

jEdit is Java based and can run on any platform that supports Java. It supports syntax highlighting for over 100 languages, including all the main Ajax ones. Several more advanced features are available through a plug-in system, which is well integrated. Plug-ins can be automatically browsed, downloaded, and installed from within jEdit itself. Useful plug-ins include support for syntax checkers, debuggers, compilers, and version-control interfaces, and specific support for CSS and XSLT.

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Figure A.1 Syntax highlighting support for JavaScript in (left to right) the TextPad, Gvim, and jEdit programmer’s editors

Vim and Emacs are powerful extensible text editors with a long tradition in UNIX operating systems, although both have been ported to Windows, too. Both have well-developed modes for JavaScript coding.

Integrated development environments

Enterprise programming languages such as .NET and Java have a long history of integrated development environments. The market for these is mature, and in recent years, a number of mature, feature-rich open source and freeware IDEs have appeared. IDEs designed for server-side coding languages are often extensible enough to allow for client-side development using Ajax.

Microsoft technologies are still dominated by Microsoft’s own Visual Studio. Visual Studio includes support for web development through the Visual InterDev

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component, which supports JavaScript and CSS. Free, cut-down versions have recently become available under the name Visual Studio Express, including one targeted at web developers.

The most prominent Java IDE at present is the IBM-sponsored Eclipse. Eclipse is mostly a Java development tool and ships with a complex set of plug-ins specifically written for Java developers. A thriving plug-in community exists, including some relatively simple JavaScript plug-ins providing syntax highlighting and outline views of methods and classes (figure A.2).

With the recent Eclipse version 3.1, a broader range of web developer plugins is being developed by the Web Tools Platform project, which in addition to supporting server-side J2EE technologies, has editors for JavaScript, XML, HTML, and CSS. Eclipse also offers strong project-level codebase-management features and full integration with CVS version control out of the box. Third-party integration with Subversion, Visual SourceSafe, and other version-control systems is available.

Some enterprise Java development tools such as the Sun Java Studio Creator and SAP NetWeaver offer high-level design facilities for web applications. In our experience, these are based heavily on the classic web application metaphor, with an application being modeled as a series of discrete pages, and may translate poorly to the Ajax approach. Studio Creator uses Java ServerFaces (JSF) behind the scenes, however. We discussed JSF and Ajax in chapter 5, and although the two technologies have some challenges to overcome before being fully interoperable, it may be possible that JSF-based tools will support Ajax better in the near future.

Figure A.2 The JavaScript editor plug-in for Eclipse provides rudimentary outlining support for JavaScript objects but doesn’t handle the full object-based syntax.

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As well as having a foot in the enterprise-development camp, Ajax has roots in the web-design community, for whom an entirely different type of toolset has developed. Macromedia Dreamweaver and Microsoft FrontPage are two notable web-design tools of this type, and both offer support for the basic client-side technologies used by Ajax. Dreamweaver provides good support for basic JavaScript and CSS editing (figure A.3) and a two-way HTML editor with visual and text modes, but for WYSIWYG orchestration of complex JavaScript user interfaces, it supports only its own code library. Integrating third-party libraries such as x, Prototype, and Rico into a Dreamweaver or FrontPage project would require a lot of hand-crafting the scripts, making use of the text editor functionality of the tools and relatively little else.

The final tool worth a mention here is ActiveState’s Komodo, which is a crosslanguage scripting IDE, supporting Perl, Python, PHP, Tcl, JavaScript, and XSLT. Komodo has very good support for JavaScript codebase navigation and a sophis-

Figure A.3 Dreamweaver’s editor supports JavaScript and CSS. The CSS file being edited in the upper-right pane is also shown in outline form in the upper left.