Set a JSON object in a Javascript function and pass it to another function -

i'm trying set json object javascript function , use parameter in function, obj has no value outside function. created json object outside function:

var obj = {"level":0, "index":0, "count":0, "aabb":[], "point":[], "children":[]}; 

then

function loadxmldoc()   {      if(window.xmlhttprequest){       xmlhttp=new xmlhttprequest();    } else {       xmlhttp=new activexobject("microsoft.xmlhttp");    }    xmlhttp.onreadystatechange=function(){       if(xmlhttp.readystate==4 && xmlhttp.status==200){         var string = xmlhttp.responsetext;         obj = json.parse(string);         document.getelementbyid("mydiv").innerhtml = obj.children;       }    }    xmlhttp.open("get","r0.json",true);    xmlhttp.send();     return obj;     } 

but after call function , pass obj, this:

    var obj = loadxmldoc();     initgl(canvas);     initshaders();     initbuffers(obj); 

it cannot pass value function initbuffers. why did happen , how can solve that? thanks.

i not sure mean when cannot pass obj parameter, 1 thing realize onreadystatechange handler called asynchronously, after call initbuffers. perhaps, need call initialization routines inside handler, when json response parsed.