ramblings/oxygen/js-debugger/README.md

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# Opening a JavaScript debugger within Oxygen [JS Operations](https://www.oxygenxml.com/doc/versions/23.1/ug-editor/topics/dg-default-author-operations.html#dg-default-author-operations__jsoperation)
Even though its authors state that this operation "[can be used to execute small pieces of Javascript code](https://github.com/oxygenxml/javascript-sample-operations)",
all the Oxygen and Java public APIs are exposed and this operation can be used for fairly complex tasks.
The main limitation is then the lack of a debugger and relying on logs rapidly becomes very tedious to develop complex code.
The good news is that Oxygen uses Mozilla's [Rhino JavaScript engine](https://en.wikipedia.org/wiki/Rhino_(JavaScript_engine)) and that this engine comes with a
[debugger](https://www-archive.mozilla.org/rhino/debugger.html).
This rambling proposes a way to launch the debugger from a JS Operation.
## Installation
To do so, add this function to your commons.js file:
```javascript
startDebugger = function () {
var runnable = {
run: function () {
main.dispose();
}
}
var context = Packages.org.mozilla.javascript.Context.getCurrentContext(); // Within the current context...
var contextFactory = context.getFactory();
var scope = Packages.org.mozilla.javascript.tools.shell.Environment(runnable.__parent__); // and the scope of the runnable variable's parent ...
var main = Packages.org.mozilla.javascript.tools. debugger.Main.mainEmbedded(contextFactory, scope, 'Debugger'); // start a debugging session ...
main.setExitAction(java.lang.Runnable(runnable)); // , clean the resources at exit time...
main.setVisible(true); // and make it visible/
}
```
And use it in the script parameter of the JS operation:
```javascript
doOperation = startDebugger;
```
To call the action which uses this operation, you can attach it to a menu or tool icon or just define a shortkey and you're done !
Call this action and you'll pop up a nice vintage debugger :
![debugger.jpg](debugger.jpg)
Use the File menu to open or run the file to debug (such as [test.js]):
![debugger2.jpg](debugger2.jpg)
There are a few things to know before using it, though...
## Limitations
### Scope
I haven't found a way to simply grab the current scope object in JavaScript and the closest method I have found is:
```javascript
Packages.org.mozilla.javascript.tools.shell.Environment(runnable.__parent__)
```
This creates a scope with everything in the runnable's parent's scope augmented with the environment variables with may not be present in the current scope.
All the other methods I have tried gave scopes which were, on the contrary, reduced compared to the current scope and lacking, for instance, the authorAcces object
without which you can't interact with Oxygen.
### Functions seen as objects
Just try it by yourself in the "evaluate" window:
```javascript
function a() {}
b = function() {}
```
"a" is seen as an object and not as a function, meaning that you can't call it. "b" is, correctly, seen as a function.
### Strict behavior on instanciation.
The word "new" is mandatory when instanciating a "class" (which is not the case when a JS operation script is run out of the debugger):
```javascript
aclass = function () {
this.setFoo(1);
return this;
}
aclass.prototype.setFoo = function (v) {
this.foo = v;
}
anObject = new aclass() ; // works as expected
anobject = aclass(); // fails with a message saying that there is no setFoo function in the object
```
# Framework
This directory includes the Oxygen sample framework on which ou can test the debugger but it should work on any framework.