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 我猜你的问题是#mapCanvas不在DOM中，直到你尝试访问它，所以这个： 
 
document.getElementById('mapCanvas')
 
 会给你一个无用的null 。 在使用之前，您需要等待#mapCanvas在DOM中; 你不能做这样的事情： 
 
map_canvas = this.$el.find('#mapCanvas')[0];
 
 这会给你一个有效的ID，但你会混淆谷歌地图的功能，因为它不会有一个大小，所以地图将呈现奇怪。 这会让您回想起在绑定您的Google地图资料之前等待DOM中的所有内容。 
 
 解决这个问题的一个方法是使用延迟为零的setTimeout ： 
 
var _this = this;
setTimeout(function() { _this.renderMap() }, 0);
 
 这看起来有点奇怪，但这个技巧基本上会将renderMap调用转储到浏览器的工作队列中，并且一旦将控制权返回给浏览器，它就会运行。 
 
 你也可以使用_.defer ： 
 
 
 
 推迟 _.defer(function, [*arguments]) 
 
 
 延迟调用函数，直到当前调用堆栈已被清除，类似于使用延迟为0的setTimeout 。用于执行昂贵的计算或块中的HTML渲染，而不阻止UI线程更新。 
 
 
 这可能是一个更好的选择，因为它使你的意图明确。 

I'd guess that your problem is that #mapCanvas isn't in the DOM until after you try to access it so this:
 
document.getElementById('mapCanvas')
 
will give you a useless null. You need to wait until #mapCanvas is in the DOM before using it; you can't do something like this either:
 
map_canvas = this.$el.find('#mapCanvas')[0];
 
That will give you a valid ID but you'll confuse the Google Maps functions because it won't have a size so the map will be rendered oddly. This puts you back to waiting for everything to be in the DOM before binding your Google Maps stuff.
 
One way around this is to use setTimeout with a delay of zero:
 
var _this = this;
setTimeout(function() { _this.renderMap() }, 0);
 
This looks strange bit it does work, this trick basically dumps your renderMap call into the browser's work queue and it'll get around to running it once you've returned control to the browser.
 
You can also use _.defer:
 
 
 
defer _.defer(function, [*arguments])
 
 
Defers invoking the function until the current call stack has cleared, similar to using setTimeout with a delay of 0. Useful for performing expensive computations or HTML rendering in chunks without blocking the UI thread from updating.
 
 
This might be a better choice as it makes your intent explicit.