v8  5.5.372(node7.10.1)
V8 is Google's open source JavaScript engine
Debug Class Reference

#include <v8-debug.h>

Data Structures

class  ClientData
class  EventDetails
class  Message

Public Types

typedef void(* EventCallback) (const EventDetails &event_details)
typedef void(* MessageHandler) (const Message &message)
typedef void(* DebugMessageDispatchHandler) ()

Static Public Member Functions

static bool SetDebugEventListener (Isolate *isolate, EventCallback that, Local< Value > data=Local< Value >())
static void DebugBreak (Isolate *isolate)
static void CancelDebugBreak (Isolate *isolate)
static bool CheckDebugBreak (Isolate *isolate)
static void SetMessageHandler (Isolate *isolate, MessageHandler handler)
static void SendCommand (Isolate *isolate, const uint16_t *command, int length, ClientData *client_data=NULL)
static MaybeLocal< ValueCall (Local< Context > context, v8::Local< v8::Function > fun, Local< Value > data=Local< Value >())
static MaybeLocal< ValueGetMirror (Local< Context > context, v8::Local< v8::Value > obj)
static void ProcessDebugMessages (Isolate *isolate)
static Local< ContextGetDebugContext (Isolate *isolate)
static MaybeLocal< ContextGetDebuggedContext (Isolate *isolate)
static void SetLiveEditEnabled (Isolate *isolate, bool enable)
static MaybeLocal< ArrayGetInternalProperties (Isolate *isolate, Local< Value > value)
static bool IsTailCallEliminationEnabled (Isolate *isolate)
static void SetTailCallEliminationEnabled (Isolate *isolate, bool enabled)

Detailed Description

Definition at line 26 of file v8-debug.h.

Member Typedef Documentation

◆ DebugMessageDispatchHandler

typedef void(* DebugMessageDispatchHandler) ()

Callback function for the host to ensure debug messages are processed.

Definition at line 156 of file v8-debug.h.

◆ EventCallback

typedef void(* EventCallback) (const EventDetails &event_details)

Debug event callback function.

event_detailsobject providing information about the debug event

A EventCallback2 does not take possession of the event data, and must not rely on the data persisting after the handler returns.

Definition at line 141 of file v8-debug.h.

◆ MessageHandler

typedef void(* MessageHandler) (const Message &message)

Debug message callback function.

messagethe debug message handler message object

A MessageHandler2 does not take possession of the message data, and must not rely on the data persisting after the handler returns.

Definition at line 151 of file v8-debug.h.

Member Function Documentation

◆ Call()

static MaybeLocal<Value> Call ( Local< Context context,
v8::Local< v8::Function fun,
Local< Value data = LocalValue >() 

Run a JavaScript function in the debugger.

funthe function to call
datapassed as second argument to the function With this call the debugger is entered and the function specified is called with the execution state as the first argument. This makes it possible to get access to information otherwise not available during normal JavaScript execution e.g. details on stack frames. Receiver of the function call will be the debugger context global object, however this is a subject to change. The following example shows a JavaScript function which when passed to v8::Debug::Call will return the current line of JavaScript execution.
function frame_source_line(exec_state) {
return exec_state.frame(0).sourceLine();

◆ CancelDebugBreak()

static void CancelDebugBreak ( Isolate isolate)

◆ CheckDebugBreak()

static bool CheckDebugBreak ( Isolate isolate)

◆ DebugBreak()

static void DebugBreak ( Isolate isolate)

◆ GetDebugContext()

static Local<Context> GetDebugContext ( Isolate isolate)

Debugger is running in its own context which is entered while debugger messages are being dispatched. This is an explicit getter for this debugger context. Note that the content of the debugger context is subject to change. The Context exists only when the debugger is active, i.e. at least one DebugEventListener or MessageHandler is set.

◆ GetDebuggedContext()

static MaybeLocal<Context> GetDebuggedContext ( Isolate isolate)

While in the debug context, this method returns the top-most non-debug context, if it exists.

◆ GetInternalProperties()

static MaybeLocal<Array> GetInternalProperties ( Isolate isolate,
Local< Value value 

Returns array of internal properties specific to the value type. Result has the following format: [<name>,


]. Result array will be allocated in the current context.

◆ GetMirror()

static MaybeLocal<Value> GetMirror ( Local< Context context,
v8::Local< v8::Value obj 

Returns a mirror object for the given object.

◆ IsTailCallEliminationEnabled()

static bool IsTailCallEliminationEnabled ( Isolate isolate)

Defines if the ES2015 tail call elimination feature is enabled or not. The change of this flag triggers deoptimization of all functions that contain calls at tail position.

◆ ProcessDebugMessages()

static void ProcessDebugMessages ( Isolate isolate)

Makes V8 process all pending debug messages.

From V8 point of view all debug messages come asynchronously (e.g. from remote debugger) but they all must be handled synchronously: V8 cannot do 2 things at one time so normal script execution must be interrupted for a while.

Generally when message arrives V8 may be in one of 3 states:

  1. V8 is running script; V8 will automatically interrupt and process all pending messages;
  2. V8 is suspended on debug breakpoint; in this state V8 is dedicated to reading and processing debug messages;
  3. V8 is not running at all or has called some long-working C++ function; by default it means that processing of all debug messages will be deferred until V8 gets control again; however, embedding application may improve this by manually calling this method.

Technically this method in many senses is equivalent to executing empty script:

  1. It does nothing except for processing all pending debug messages.
  2. It should be invoked with the same precautions and from the same context as V8 script would be invoked from, because: a. with "evaluate" command it can do whatever normal script can do, including all native calls; b. no other thread should call V8 while this method is running (v8::Locker may be used here).

"Evaluate" debug command behavior currently is not specified in scope of this method.

◆ SendCommand()

static void SendCommand ( Isolate isolate,
const uint16_t *  command,
int  length,
ClientData client_data = NULL 

◆ SetDebugEventListener()

static bool SetDebugEventListener ( Isolate isolate,
EventCallback  that,
Local< Value data = LocalValue >() 

◆ SetLiveEditEnabled()

static void SetLiveEditEnabled ( Isolate isolate,
bool  enable 

Enable/disable LiveEdit functionality for the given Isolate (default Isolate if not provided). V8 will abort if LiveEdit is unexpectedly used. LiveEdit is enabled by default.

◆ SetMessageHandler()

static void SetMessageHandler ( Isolate isolate,
MessageHandler  handler 

◆ SetTailCallEliminationEnabled()

static void SetTailCallEliminationEnabled ( Isolate isolate,
bool  enabled 

The documentation for this class was generated from the following file: