封装ajax

// 封装ajax
var request = (url, type = "get", data = "", header, async = true) => {
  console.log(header);
  var headers = {};
  switch (header) {
    case 1:
      headers["Content-Type"] = "application/x-www-form-urlencoded";//post提交表单  key1=val1&key2=val2 的方式进行编码
      break;
    case 2:
      headers["Content-Type"] = "multipart/form-data";//post提交表单  上传文件时使用
      break;
    case 3:
      headers["Content-Type"] = "text/xml";//用于xml的数据交换格式
      break;
    case 4:
      headers["Content-Type"] = "application/json";//向后端传递json字符串
      data = JSON.stringify(data);
      break;
  }
  var option = {
    type,
    url,
    data,
    async,
    // headers,
  }
  if (header) {//如果给header传参了
    console.log("进来");
    option.headers = headers;
  }
  console.log(option);
  return new Promise((resolve, reject) => {
    $.ajax({
      ...option,
      success (res) {
        resolve(res);
      },
      error (err) {
        reject(err)
      }
    })
  })
}

//简易封装
function getAjax( _methods , url , _data) {
    return new Promise((resolve,reject) => {
        let xhr;
        if(XMLHttpRequest){
            xhr = new XMLHttpRequest()
        }else{
            xhr = new ActiveXObject()
        }
        let data = _data || null;
        let methods = _methods || 'get';
        xhr.open(methods,url,true)
        xhr.send(data)
        xhr.onreadystatechange = () => {
            if(xhr.readyState == 4){
                if(xhr.status == 200){
                    resolve(JSON.parse(xhr.responseText) )
                }
                else{
                    reject(JSON.parse(xhr.responseText) )
                }
            }
        }
    })
}

getAjax('post','http://showme2.myhope365.com/api/cms/category/open/list',{
    pageNum:10,
    pageSize:1
}).then(res => {
    console.log(res)
})