ECMAScript for Extensible Markup Language is an extension that lets a script treat a markup document as a value. The script can read elements, filter them, and build new markup without first converting the document into a tree of generic objects. The extension was standardized and later overtaken by other ways of handling markup in scripts.
The markup it was built for is eXtensible Markup Language (XML). A script reads and writes that markup directly. A later library can do the same job without this particular extension.
What the Extension Added
- A literal. Markup could appear in the script as markup, not as a quoted string.
- Navigation. Child elements and attributes could be reached from the value.
- A filter. A condition could select only the elements that matched.
This Extension and a Library
| Compared | The Extension | A Markup Library |
| How markup appears in the script | As part of the language | As data passed to functions |
| Standard status | An older language extension | Whichever library the project chose |
| The document | Still markup | Still markup |