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https://github.com/pmuellr/node-debug-context

exploration of node's debug context
https://github.com/pmuellr/node-debug-context
Last synced: about 1 month ago
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exploration of node's debug context
Host: GitHub
URL: https://github.com/pmuellr/node-debug-context
Owner: pmuellr
Created: 2015-02-27T05:59:51.000Z (almost 10 years ago)
Default Branch: master
Last Pushed: 2016-01-30T23:51:00.000Z (almost 9 years ago)
Last Synced: 2024-04-09T21:04:46.829Z (9 months ago)
Language: JavaScript
Size: 7.81 KB
Stars: 1
Watchers: 3
Forks: 0
Open Issues: 1
Metadata Files:
- Readme: README.md
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README

        intro

================================================================================

An interesting feature got added to node.js 0.12 (also available in io.js):

[`vm.runInDebugContext(code)`][vmRunInDebugContext]

The documentation says "*The primary use case is to get access to

the V8 debug object*", using the following snippet:

    var vm = require("vm")

    var Debug = vm.runInDebugContext("Debug")

    Debug.setListener(_=>_)

    Debug.scripts().forEach(function(script) {

      console.log(script.name)

    })

This code snippet should list all the "scripts" V8 has loaded.  Try it, there

are **TONS** of them.

The debug context gets autocleared after the end of the vm.runInDebugContext() line.  To make things work, we need to keep the context active somehow; in this case, by doing a `Debug.setListener()`. 

So, what else can you do with this thing.  That's what I'm going to find out.

The place to figure this is out in the REPL, and also by checking out the V8

source for this stuff:

* [`debug-debugger.js`][debug-debugger.js]

* [`liveedit-debugger.js`][liveedit-debugger.js]

* [`mirror-debugger.js`][mirror-debugger.js]

* [mjsunit test cases][]

Note that a **lot** of the text here comes directly from `debug-debugger.js`.

Note that I'm going to be skipping two parts of the Debug object for now:

* `TestApi`

* `LiveEdit`

object `Debug`

================================================================================



property `DebugEvent`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `Break`

* `Exception`

* `NewFunction`

* `BeforeCompile`

* `AfterCompile`

* `CompileError`

* `PromiseEvent`

* `AsyncTaskEvent`

* `BreakForCommand`

property `ExceptionBreak`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `Caught`

* `Uncaught`

property `StepAction`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `StepOut`

* `StepNext`

* `StepIn`

* `StepMin`

* `StepInMin`

* `StepFrame`

property `ScriptType`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `Native`

* `Extension`

* `Normal`

property `ScriptCompilationType`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `Host`

* `Eval`

* `JSON`

property `ScriptBreakPointType`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `ScriptId`

* `ScriptName`

* `ScriptRegExp`

property `BreakPositionAlignment`

--------------------------------------------------------------------------------

An object with the following properties, whose values are number constants:

* `Statement`

* `BreakPosition`

method `setListener(listener, opt_data)`

--------------------------------------------------------------------------------

Sets an event listening for debug Events.

see: 

`listener` should be a function with following signature:

    function(event, exec_state, event_data, data)

* `event` will be one of the `DebugEvent` properties

* `exec_state` will be an `ExecState` object

* `event_data` is event-specific data

* `data` is the object passed to `setListener()`'s `opt_data` parameter

method `breakExecution(a)`

--------------------------------------------------------------------------------

method `breakLocations(a,b)`

--------------------------------------------------------------------------------

method `findScript(aString | aFunction | aRegExp)`

--------------------------------------------------------------------------------

Returns a `Script` object.

If the parameter is a function, the return value

is the script in which the function is defined.

If the parameter is a string,

the return value is the script for which the script name has that string

value.  

If it is a regexp and there is a unique script whose name matches

we return that, otherwise undefined.

method `scriptSource(String | Function)`

--------------------------------------------------------------------------------

Returns the script source.

If the parameter is a function the return value

is the script source for the script in which the function is defined.

If the

parameter is a string the return value is the script for which the script

name has that string value.

method `source(aFunction)`

--------------------------------------------------------------------------------

Returns the source of a function.

method `disassemble(aFunction)`

--------------------------------------------------------------------------------

Returns the disassembly of a function.

method `disassembleConstructor(aFunction)`

--------------------------------------------------------------------------------

Returns the disassembly of a constructor.

method `ExecuteInDebugContext(a,b)`

--------------------------------------------------------------------------------

method `sourcePosition(a)`

--------------------------------------------------------------------------------

method `findFunctionSourceLocation(a,b,c)`

--------------------------------------------------------------------------------

method `findScriptSourcePosition(a,b,c)`

--------------------------------------------------------------------------------

method `findBreakPoint(a,b)`

--------------------------------------------------------------------------------

method `findBreakPointActualLocations(a)`

--------------------------------------------------------------------------------

method `setBreakPoint(a,b,c,d)`

--------------------------------------------------------------------------------

method `setBreakPointByScriptIdAndPosition(???)`

--------------------------------------------------------------------------------

method `enableBreakPoint(a)`

--------------------------------------------------------------------------------

method `disableBreakPoint(a)`

--------------------------------------------------------------------------------

method `changeBreakPointCondition(a,b)`

--------------------------------------------------------------------------------

method `changeBreakPointIgnoreCount(a,b)`

--------------------------------------------------------------------------------

method `clearBreakPoint(a)`

--------------------------------------------------------------------------------

method `clearAllBreakPoints()`

--------------------------------------------------------------------------------

method `disableAllBreakPoints()`

--------------------------------------------------------------------------------

method `findScriptBreakPoint(a,b)`

--------------------------------------------------------------------------------

method `setScriptBreakPoint(???)`

--------------------------------------------------------------------------------

method `setScriptBreakPointById(???)`

--------------------------------------------------------------------------------

method `setScriptBreakPointByName(???)`

--------------------------------------------------------------------------------

method `setScriptBreakPointByRegExp(???)`

--------------------------------------------------------------------------------

method `enableScriptBreakPoint(a)`

--------------------------------------------------------------------------------

method `disableScriptBreakPoint(a)`

--------------------------------------------------------------------------------

method `changeScriptBreakPointCondition(???)`

--------------------------------------------------------------------------------

method `changeScriptBreakPointIgnoreCount(???)`

--------------------------------------------------------------------------------

method `scriptBreakPoints()`

--------------------------------------------------------------------------------

method `clearStepping()`

--------------------------------------------------------------------------------

method `setBreakOnException()`

--------------------------------------------------------------------------------

method `clearBreakOnException()`

--------------------------------------------------------------------------------

method `isBreakOnException()`

--------------------------------------------------------------------------------

method `setBreakOnUncaughtException()`

--------------------------------------------------------------------------------

method `clearBreakOnUncaughtException()`

--------------------------------------------------------------------------------

method `isBreakOnUncaughtException()`

--------------------------------------------------------------------------------

method `showBreakPoints(a,b,c)`

--------------------------------------------------------------------------------

method `scripts()`

--------------------------------------------------------------------------------

Returns an array of `Script` objects

method `debuggerFlags()`

--------------------------------------------------------------------------------

Returns an object with the following properties:

* `breakPointsActive`

* `breakOnCaughtException`

* `breakOnUncaughtException`

Each of these properties is an object with a `getValue()` and `setValue()`

method, which get and set the boolean value of the property.

method `MakeMirror(a,b)`

--------------------------------------------------------------------------------

object `Script`

================================================================================

A `Script` object has the following properties:

* `id` - Number

* `name` - String

* `source` - String

* `type` - value of `Debug.ScriptType`

* `compilation_type` - value of `Debug.ScriptCompilationType`

* `column_offset` - Number

* `line_offset` - Number

* `line_ends` - array of Number

* `context_data` - ???

* `eval_from_script` - ???

* `eval_from_script_position` - ???

* `eval_from_function_name` - ???

* `source_url` - ???

* `source_mapping_url` - ???

object `ExecState`

================================================================================

[vmRunInDebugContext]:  https://iojs.org/api/vm.html#vm_vm_runindebugcontext_code

[debug-debugger.js]:    https://github.com/iojs/io.js/blob/v1.x/deps/v8/src/debug-debugger.js

[liveedit-debugger.js]: https://github.com/iojs/io.js/blob/v1.x/deps/v8/src/liveedit-debugger.js

[mirror-debugger.js]:   https://github.com/iojs/io.js/blob/v1.x/deps/v8/src/mirror-debugger.js

[mjsunit test cases]:   https://github.com/iojs/io.js/blob/v1.x/deps/v8/test/mjsunit/