Accessing variables trapped by closure

Question

I was wondering if there is any way to access variables trapped by closure in a function from outside the function; e.g. if I have:

A = function(b) {
    va         


        

Answer 1

Variables within a closure aren't directly accessible from the outside by any means. However, closures within that closure that have the variable in scope can access them, and if you make those closures accessible from the outside, it's almost as good.

Here's an example:

var A = function(b) {
    var c = b + 100;
    this.access_c = function(value) {
        // Function sets c if value is provided, but only returns c if no value
        // is provided
        if(arguments.length > 0)
            c = value;
        return c;
    };
    this.twain = function() {
        return 2 * c;
    };
};
var a_inst = new A(123);
var my_c = a_inst.access_c();
// my_c now contains 223
var my_2c = a_inst.twain();
// my_2c contains 446
a_inst.access_c(5);
// c in closure is now equal to 5
var newer_2c = a_inst.twain();
// newer_2c contains 10

Hopefully that's slightly useful to you...