The best things I like about JSEclipse are:
- Code completion for JavaDoc.
- Function and class names are displayed in the Outline panel for the currently open file.
- Open declaration i.e. the famous F3 functionality
- Error reporting
- Warning reporting
- Code wrap
- Code completion uses Rhino for better accuracy
- Use of JSDoc and inline parameter comments to detect parameter type
- Suggest parameters to be filled
- Project dependent code completion
- Reads all classes in current project
- Reads classes in currently opened files
- Scan current file for words
- Reads XML files for class definitions
- Add your own XML with class definitions
It appears to work based on usage - it remembers how an object is used and completes based on that.