Javascript trans data to qml have problems

[skyitachi]

./
main.qml
Test.qml
In Test.qml
@import QtQuick 2.0
import QtQuick.LocalStorage 2.0 as Sql
QtObject{
id:weatherInfo
property var db: null
property var result: []
function getCurWeatherInfo(cityname)
{
var doc = new XMLHttpRequest();
//a function to be called automatically when the readyState changed
var cityID = getCityIDs(cityname);
//result=new Array;
doc.open("GET", qsTr("xxxxx.html").arg(cityID));
//weatherArray[0] = new Array;
doc.onreadystatechange = function() {
if (doc.readyState == XMLHttpRequest.DONE) {
var jsonObject = eval('(' + doc.responseText + ')');
result['temp']=jsonObject['weatherinfo']['temp']
result['city']=jsonObject['weatherinfo']['city']
console.log(result['temp']);
console.log(result['city']);
}
}
doc.send();
}
}
}
@

In main.qml
@
Rectangle{
id:rect
Test{
id:testItem
}
Button{
id:someButton
onClicked:{
testItem. getCurWeatherInfo(cityname)
console.log(testItem.result['temp'] + " "+ result['city'])
}
}
}
@
my quesion is that :
why in main.qml output:
undefined undefined
in Test.qml output:
27 city

it is very confusing , I have set result property in Test.qml, it should be a global var in Test.qml but why in func getCurWeatherInfo() it cannot be updated.

PS: it is a trick about javascript asynchronous function???
I need everyone's help, thanks

[skyitachi]

I use a way to solve this problem, use result as a parameter in getCurweatherInfo(cityName, result),it can be ok.
PS: it seemed very silly,because I am a javascript and qml freshman.