CORS 请求在 Safari 中不起作用

I am making a CORS xhr request. This works fine in chrome, however when I run in safari I get an 'Can not load ---- access not allowed by Access-control-allow-origin'. The code is exactly the same and I have set the CORS on the server. Below is my code.(has access control, but you are free to try without the accessToken)

 var water;
 var req = new XMLHttpRequest;
 req.overrideMimeType("application/json");
 req.open('GET', 'https://storage.googleapis.com/fflog/135172watersupplies_json', true);
 req.setRequestHeader('Authorization', 'Bearer ' + accessToken);
 origThis = this;
 var target = this;
 req.onload = function() {
 water = req;

 req.send(null);

查看请求标头后，我看到首先发出了一个 OPTIONS 请求，这是不允许的请求.原始标头不包含在 Safari 的响应中，但在 chrome 中.这是什么原因造成的.任何帮助将不胜感激.