node_modules/websocket/node_modules/nan/doc/callback.md

   1 ## Nan::Callback
   2
   3 `Nan::Callback` makes it easier to use `v8::Function` handles as callbacks. A class that wraps a `v8::Function` handle, protecting it from garbage collection and making it particularly useful for storage and use across asynchronous execution.
   4
   5  - <a href="#api_nan_callback"><b><code>Nan::Callback</code></b></a>
   6
   7 <a name="api_nan_callback"></a>
   8 ### Nan::Callback
   9
  10 ```c++
  11 class Callback {
  12  public:
  13   Callback();
  14
  15   explicit Callback(const v8::Local<v8::Function> &fn);
  16
  17   ~Callback();
  18
  19   bool operator==(const Callback &other) const;
  20
  21   bool operator!=(const Callback &other) const;
  22
  23   v8::Local<v8::Function> operator*() const;
  24
  25   MaybeLocal<v8::Value> operator()(AsyncResource* async_resource,
  26                                    v8::Local<v8::Object> target,
  27                                    int argc = 0,
  28                                    v8::Local<v8::Value> argv[] = 0) const;
  29
  30   MaybeLocal<v8::Value> operator()(AsyncResource* async_resource,
  31                                    int argc = 0,
  32                                    v8::Local<v8::Value> argv[] = 0) const;
  33
  34   void SetFunction(const v8::Local<v8::Function> &fn);
  35
  36   v8::Local<v8::Function> GetFunction() const;
  37
  38   bool IsEmpty() const;
  39
  40   void Reset(const v8::Local<v8::Function> &fn);
  41
  42   void Reset();
  43
  44   MaybeLocal<v8::Value> Call(v8::Local<v8::Object> target,
  45                             int argc,
  46                             v8::Local<v8::Value> argv[],
  47                             AsyncResource* async_resource) const;
  48   MaybeLocal<v8::Value> Call(int argc,
  49                              v8::Local<v8::Value> argv[],
  50                              AsyncResource* async_resource) const;
  51
  52   // Deprecated versions. Use the versions that accept an async_resource instead
  53   // as they run the callback in the correct async context as specified by the
  54   // resource. If you want to call a synchronous JS function (i.e. on a
  55   // non-empty JS stack), you can use Nan::Call instead.
  56   v8::Local<v8::Value> operator()(v8::Local<v8::Object> target,
  57                                   int argc = 0,
  58                                   v8::Local<v8::Value> argv[] = 0) const;
  59
  60   v8::Local<v8::Value> operator()(int argc = 0,
  61                                   v8::Local<v8::Value> argv[] = 0) const;
  62   v8::Local<v8::Value> Call(v8::Local<v8::Object> target,
  63                             int argc,
  64                             v8::Local<v8::Value> argv[]) const;
  65
  66   v8::Local<v8::Value> Call(int argc, v8::Local<v8::Value> argv[]) const;
  67 };
  68 ```
  69
  70 Example usage:
  71
  72 ```c++
  73 v8::Local<v8::Function> function;
  74 Nan::Callback callback(function);
  75 callback.Call(0, 0);
  76 ```