Xebug (say: zee-bug) is a universal debugger for JavaScript, written in JavaScript. It will work in any JavaScript environment that provides a blocking input API (the prompt() function or synchronous XMLHttpRequest in web browsers, for example) and the opportunity to intercept JavaScript code before it is evaluated (hooks in client-side loaders, or via a HTTP proxy, etc).
Xebug works by automatically instrumenting JavaScript code with hooks into Xebug, therefore it incurs a significant performance penalty when enabled.
Currently the instrumentation is done using the JavaScript parser included with the [Narcissus](http://en.wikipedia.org/wiki/Narcissus_(JavaScript_engine\)) JavaScript interpreter (though the interpreter itself is not used).
Xebug is still in development but a working demo can be seen at http://tlrobinson.net/xebug-demo. This demo provides a GDB-like command-line interface ("XDB"), but graphical interfaces are also possible.
Xebug can also be used on languages that compile to JavaScript, like Objective-J and CoffeeScript. Their compilers could be modified to generate instrumented code with accurate line numbers and source code in the original language.
Xebug is currently licensed under the GPL, but will likely be released under a more permissive license in the future.
- Single step in, out, next, continue
- Breakpoints
- Watchpoints
- Backtraces
- Instrumentation via a special JSGI webserver or hook loaders directly via JavaScript API
- Code coverage reporting
- XDB, a GDB-like command-line interface
- Partially implements the V8 debugger protocol
- Complete V8 debugger protocol conversion
- Refactor UI, XDB, and core
- Integrate with various loaders (Objective-J, Narwhal, other CommonJS, etc)
- Auto-instrumenting web proxy
- Sychronous XHR frontend
- CommonJS frontends
- GUI
To build:
Xebug Universal JavaScript Debugger Copyright (C) 2010 Thomas Robinson (http://tlrobinson.net/)
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.