Google Map同步地址解析延迟 [英] Google map sync geocode delay

问题描述

就是这样， jsfiddle

如您所见，我打算为Google地图功能创建单独的功能. locate_self()函数用于返回当前地理位置的纬度坐标，而initialize_map()函数用于绘制地图并接受可选的预定义坐标，否则，请使用默认的随机坐标.

As you can see, I intend to make separate functions for google map features. The locate_self() function is used to return latlng coordinates of current geolocation while the initialize_map() function draws the map and accept optional predefined coordinated otherwise, use a default random coordinates.

问题在于，initialize_map()的发射速度比locate_self()快，将返回的元素渲染为undefined，最后，initialize_map()使用默认坐标.

The problem is, initialize_map() fired faster than locate_self(), rendering the returned element as undefined and finally, initialize_map() goes with default coordinate.

在locate_self()内，我给出一个alert()以及当前的地理位置坐标来创建一个测试块，以指示此功能正常工作.

Inside locate_self(), I created a test block by giving an alert(), along with current geolocation coordinates to indicates that this function is working properly.

问题是我如何让initialize_map() 等待等待locate_self()，直到它返回坐标而不是undefined?

The question is how do I make initialize_map() wait for locate_self() until it returns the coordinate rather than undefined ?

我稍后将对接收latlng并返回地址字符串的函数使用相同的解决方案. Geocoder也具有相同的延迟".

I will use the same solution later for function that accept latlng and return address string. Geocoder also have the same kind of 'delay'.

我以前尝试过使用超时，但是它仍然给我未定义的(也许我不知道放置超时块，我不知道).

I tried using timeout before but it still giving me undefined (maybe I was wrong placing the timeout block, I don't know).

谢谢，如果这是转贴，我感到非常抱歉

Thanks and I'm very sorry if this is a repost

推荐答案

地理位置服务是异步的.解决此问题的最简单方法是使用回调而不是使用return:

The geolocation service is asynchronous. The simplest way around this is to use a callback instead of using return:

function initialize_map(result) {
  if (result !== 'error') {
    gm_map = new google.maps.Map(gm_map_container, gm_map_options);
    if (!result) {
      result = new google.maps.LatLng(-34.397, 150.644);
    }
    gm_map.setCenter(result);
  }
}

function locate_self(callback) {
  if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(function (position) {
      var pos = new google.maps.LatLng(position.coords.latitude, position.coords.longitude);
      callback(pos);
    });
  } else { callback('error'); }
}

locate_self(initialize_map);

演示.

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