JavaScript pass scope to another function

The only way to truly get access to function a's private scope is to declare b inside of a so it forms a closure that allows implicit access to a's variables.

Here are some options for you.

Direct Access

1. Declare b inside of a.

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

2. If you don't want b inside of a, then you could have them both inside a larger container scope:

   function container() {   var x, obj;   function a(){      x = 5;      obj = {..};      b();   }   function b(){      // access x or obj...   }}container.a();

These are the only ways you're going to be able to use a's variables directly in b without some extra code to move things around. If you are content with a little bit of "help" and/or indirection, here are a few more ideas.

Indirect Access

1. You can just pass the variables as parameters, but won't have write access except to properties of objects:

   function a() {   var x = 5,      obj = {};   b(x, obj);}function b(x, obj){   // access x or obj...   // changing x here won't change x in a, but you can modify properties of obj}a();

   As a variation on this you could get write access by passing updated values back to a like so:

   // in a:var ret = b(x, obj);x = ret.x;obj = ret.obj;// in b:return {x : x, obj : obj};

2. You could pass b an object with getters and setters that can access a's private variables:

   function a(){   var x = 5,      obj = {..},      translator = {         getX : function() {return x;},         setX : function(value) {x = value;},         getObj : function() {return obj;},         setObj : function(value) {obj = value;}      };   b(translator);}function b(t){   var x = t.getX(),      obj = t.getObj();   // use x or obj...   t.setX(x);   t.setObj(obj);   // or you can just directly modify obj's properties:   obj.key = value;}a();

   The getters and setters could be public, assigned to the this object of a, but this way they are only accessible if explicitly given out from within a.

3. And you could put your variables in an object and pass the object around:

   function a(){   var v = {      x : 5,      obj : {}   };   b(v);}function b(v){   // access v.x or v.obj...   // or set new local x and obj variables to these and use them.}a();

   As a variation you can construct the object at call time instead:

   function a(){   var x = 5,      obj = {};   b({x : x, obj: obj});}function b(v){   // access v.x or v.obj...   // or set new local x and obj variables to these and use them.}a();

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()}

what about using bind

function funcA(param) {         var bscoped = funcB.bind(this);         bscoped(param1,param2...)}