Object initialization problem - not null inside function but is null when I exit function

I have code like this ( I have used Dojo for classes ):

var current_div=null;
var current_element=null;
var elements_container=null;
var status_container=null;

function main(){
    //alert(status_container==null);
    load_status_system();
    //alert(status_container==null);
    load_ring_topology();
    //alert(status_container==null);
}

inside load_status_system I set function load_status_system() {

 dojo.xhrGet({
        url: "dynamic/status-system.json",
        handleAs: "json",
        load: function(obj) {开发者_JAVA百科
            status_container=new STATUS_CONTAINER(obj);
            alert(status_container==null);
        },
        error: function(err) {
            alert('error during loading status-system.json');
        }
    });
}

Problem is that I get status_container null outside function but inside function it is not null. What is wrong with this code ? How to initialize status_container not to be null outside the function ?

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Your scoping seems to be fine. I think you’re wrestling with the asynchronous nature of Ajax calls.

As posted, the order of execution of your code is as follows:

1. function main
2. main => load_status_system()
3. load_status_system => dojo.xhrGet
4. main => load_ring_topology()
5. function main is done and exits (status_container is still null)
6. dojo.xhrGet receives its response, calls load()
7. load => fills status_container
8. load alerts the new status_container and exits.
9. your code is done running

The solution to your problem would be to tell xhrGet to do its call synchronously. I’ve never used Dojo, so I don’t know how to do that. Usually it’s done by setting the async property of the XHR object to false.

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This is most likely a scoping issue. I would try accessing status_container as window.status_container from within the XHR callback

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Use dojo.hitch() to specify the scope in which the function will run.