I am getting below sample json data as input,
var JSONDATA =
    {
        "MainNode": {
            "_attributes": { 
                "class": "ABC",
                "projectclass": "MyProject",
                "prjname": "PrjName",
                "enabled":"true"
            },
            "PrjProp": {
                "_attributes": {
                    "name": "MyProject.save" 
                },
                "_text": true 
            }
        }
    }
Using Jquery or Javascript, I want to get the "projectclass" value in first "_attributes". There could be multiple "_attributes" in JSON object but the requirement to the "projectclass" (fixed) from the first (fixed) "_attributes" only. 
This can be achieved like, console.log(JSONDATA.MainNode._attributes.testclass);
but "MainNode" is not fixed, this can be "OtherNode". So how to handle this is variable ? I tried , console.log(Object.keys($scope.testplan)[0]); which shows main node name but how to use this in  console.log(JSONDATA.MainNode._attributes.testclass);  as variable ?
Please suggest. Thanks
 
     
    