javascript closures and object reference

Question

i am a bit obscure situation. mainly because i thought i already grasp closures. so basically what i want is to reset to default values a collection. so let say i have collectio

Answer 1

This has nothing to do with closures. Your issue can be seen simpler with this:

var internalarray = [{x},{y},{z}];
var arr = internalarray;

// "update" internalarray here

arr === internalarray // still true
internalarray = arr; // This statement has no effect

Just like in Java, every value in JavaScript is either a primitive or a reference (a pointer to an object). The value of arr is a pointer to an object, the value of c is a pointer to an object, the value of c.internalarray is a pointer to an object, etc. Specifically in this case, c.internalarray is a pointer to an array object. Assigning one pointer to another simply makes the second one point to the object pointed to by the first one. When you do arr = internalarray; (or in your code, when you pass c.internalarray in to a function as the parameter arr), you have two pointers that point to the same object.

When you say "collection periodically get updated", you are never assigning (as in =) to c.internalarray itself. That's why arr === c.internalarray remains true -- since you assigned one to the other initially, the only way they could be not equal is if you assigned to one of them later. Instead, I am guessing you are changing the elements of the array pointed by these two variables, using subscript operator like c.internalarray[foo] = bar; or calling a method like c.internalarray.push(bar);. Since you are changing the object pointed to, multiple pointers that point to it will be able to see the changes.