在javascript中从子函数内部访问全局函数变量

Question

嗨我试图从下面的父函数中定义的子函数访问父函数内定义的变量但是当我尝试从父函数中获取并输出该函数但返回的值为null时

//PARENT FUNCTION
function getLatLong() {
var resp='';
if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(success_callback, error_callback, {
        enableHighAccuracy : true
    });
} else if (geo_position_js.init()) {
    geo_position_js.getCurrentPosition(success_callback, error_callback, {
        enableHighAccuracy : true
    });
} else {
    return false;
}
//CHILD FUNCTION
function success_callback(p) {
    var coords=[];
    coords.push(p.coords.latitude);
    coords.push(p.coords.longitude);
    resp=coords;
}

function error_callback(p) {

}

return resp;
}//END OF FUNCTION


var coords=[];

coords=getLatLong();

//logs undefined
console.log(coords);