在浏览器控制台中输入下面代码来测试：

var xhr = new XMLHttpRequest();
xhr.open('GET', 'https://www.xxx.com/api/action');
xhr.send(null);
xhr.onload = function(e) {
    var xhr = e.target;
    console.log(xhr.responseText);
}

如果接口不允许跨域访问会提示下面错误。

No 'Access-Control-Allow-Origin' header is present on the requested resource.

转载请注明出处: http://bluesd7.com/蓝影闪电的随笔/ContentId/420/跨域请求测试-Access-Control-Allow-Origin