Meanwhile, XML has become an integral part of Web development. To best utilize its power, developers must effectively create, navigate, and manipulate XML data. While innovative new programming models are designed specifically for this (e.g., XSLT, XQuery, the DOM), they are unfamiliar to many software developers. At the same time, the learning curves for these technologies are very high, so XML-based projects can require high-priced specialists for both development and maintenance.
This article explains E4X and its objective, lays out its usage with syntax and code snippets, and outlines its advantages and limitations.
The Objective of E4X
"E4X adds native XML datatypes to the ECMAScript language, extends the semantics of familiar ECMAScript operators for manipulating XML objects, and adds a small set of new operators for common XML operations, such as searching and filtering. It also adds support for XML literals, namespaces, qualified names, and other mechanisms to facilitate XML processing."
The following are some of the specific benefits of using E4X:
- Simplify the ability of Web developers to use the power of XML by using their existing skills and knowledge, and reusing familiar concepts, operators, and syntax (i.e., E4X makes XML very simple to use.)
- Standardize the syntax and semantics of a general-purpose, cross-platform, vendor-neutral set of programming language extensions by adding native XML support in ECMAScript
- Reduce code complexity, time to market, and revision cycles
- Improve performance and maintainability
- Decrease coupling between code and external data (in form of XML)
- Integrate well with other languages designed for manipulating XML, such as XPath, XSLT, and XQuery (For example, E4X should be able to invoke complementary languages when additional expressive power is needed without compromising the simplicity of the E4X language itself.)