Javascript Send Request

gistfile1.js

function sendXMLHTTPRequest (successCallback, errorCallback) {
  var request = new XMLHttpRequest(),
      url = "",
      type;
  request.open("GET", url);
  request.onreadystatechange = function () {
    if (request.readyState === 4 && request.status === 200) {
      successCallback(request.responseText); // 不判断格式直接回调
    } else {
      errorCallback("error"); // 出错回调
    }
  }
  request.send(null);
}