Question

I am using redux with react. This makes dispatch available as props in component. So when I console.log(this.props) I see following object in log under dispatch key.

[[Scopes]]: Scopes[5]
   0:Closure
   1:Closure
   2:Closure (createThunkMiddleware)
   3:Closure
   4:Global

Can someone explain what is this ?

Answer 1

[[Scopes]]是Chrome开发人员工具在C ++ here in the source内部添加和使用的私有财产。它显示函数范围内的变量，即可以从该函数访问哪些变量。

例如：

function a() {
  var foo = 'foo';
  var obj = {
    bar: function () {
      return foo;
    }
  };
  console.log(obj);
}
a();

此处，附加到属性obj.bar的函数在其范围内具有变量foo，因此当我们检查[[Scopes]] obj.bar的问题时，我们会看到类似< / p>

[[Scopes]]: Scopes[2]
0: Closure (a)
  foo: "foo"
1: Global
  (all global variables)

您可以在控制台中手动检查这些属性，这可能有助于调试，但您无法使用JavaScript访问它们，并且您不应该在应用程序代码中关注它们。

另请参阅：SO - Access function location programmatically。

What is [[Scopes]] in dispatch() of redux

1 个答案: