Javascript 谷歌地图未捕获类型错误：无法读取属性'；开始位置'；谷歌地图中未定义的

嗨，我在JS中为谷歌地图提供了这个简单的函数，我得到了未捕获的typeerror

directionResult是google directions响应对象，由其他函数传递给此函数

                var myRoute = directionResult.routes[0].legs[0];
                var warnings = document.getElementById("warnings_panel");

                for (var i=0;i<3;i++)
                {
                        warnings.innerHTML += "<br/><br/>start lat = " + myRoute.steps[i].start_location.lat() + 
                                                                    "start lng = " + myRoute.steps[i].start_location.lng() + "<br />";
                        warnings.innerHTML += "end lat = " + myRoute.steps[i].end_location.lat() + 
                                                                    "end lng = " + myRoute.steps[i].end_location.lng() + "<br /> + Path :";     

                                    for(var path=0;path<myRoute.steps[i].path.length;path++)
                                            warnings.innerHTML += myRoute.steps[i].path[path];                              



                }//

var myRoute=directionResult.routes[0]。legs[0]；
var warnings=document.getElementById（“warnings_面板”）；
对于（var i=0；i没有更多信息很难判断，但我会检查myRoute.steps数组是否至少包含三个元素。
错误是myRoute.steps的长度[myRoute.steps.length]

var myRoute = directionResult.routes[0].legs[0];
var warnings = document.getElementById("warnings_panel");
for (var i=0;i<myRoute.steps.length;i++)
{
    warnings.innerHTML += "<br/><br/>start lat = " + myRoute.steps[i].start_location.lat() + "start lng = " + myRoute.steps[i].start_location.lng() + "<br />";
    warnings.innerHTML += "end lat = " + myRoute.steps[i].end_location.lat() + "end lng = " + myRoute.steps[i].end_location.lng() + "<br /> + Path :";
    for(var path=0;path<myRoute.steps[i].path.length;path++)
        warnings.innerHTML += myRoute.steps[i].path[path];
}

var myRoute=directionResult.routes[0]。legs[0]；
var warnings=document.getElementById（“warnings_面板”）；
对于（var i=0；iOh）就是这样，它只包含一个，用于我出错的情况thanks@koool喜欢分享吗？