JavaScript pass scope to another function

Question

Is it possible to somehow pass the scope of a function to another?

For example,

function a(){
   var x = 5;
   var obj = {..};
   b()         


        

Answer 1

Have you tried something like this:

function a(){
   var x = 5;
   var obj = {..};
   b(this);
}
function b(fnA){
   //access x or obj....
   fnA.obj = 6;
}

If you can stand function B as a method function A then do this:

function a(){
   var x = 5;
   var obj = {..};
   b(this);

   this.b = function (){
      // "this" keyword is still === function a
   }
}

Answer 2

function a(){
   this.x = 5;
   this.obj = {..};
   var self = this;
   b(self);
}
function b(scope){
   //access x or obj....

}

Answer 3

Scope is created by functions, and a scope stays with a function, so the closest thing to what you're asking will be to pass a function out of a() to b(), and that function will continue to have access to the scoped variables from a().

function a(){
   var x = 5;
   var obj = {..};
   b(function() { /* this can access var x and var obj */ });
}
function b( fn ){

    fn(); // the function passed still has access to the variables from a()

}

While b() doesn't have direct access to the variables that the function passed does, data types where a reference is passed, like an Object, can be accessed if the function passed returns that object.

function a(){
   var x = 5;
   var obj = {..};
   b(function() { x++; return obj; });
}
function b( fn ){

    var obj = fn();
    obj.some_prop = 'some value'; // This new property will be updated in the
                                  //    same obj referenced in a()

}

Answer 4

No.

You're accessing the local scope object. The [[Context]].

You cannot publicly access it.

Now since it's node.js you should be able to write a C++ plugin that gives you access to the [[Context]] object. I highly recommend against this as it brings proprietary extensions to the JavaScript language.