function paramsSeralize(obj){

  if(!obj || typeof !== 'object') return obj;

  let res = '';

  for (const key in obj) {

    if (obj.hasOwnProperty(key)) {

      res += `&${key}=${obj[key]}`

    }

  }

  result = result.substring(1);

  return result;

}

function ajax (options) {

  let params = Object.assign({

    method: 'GET',

    url: '',

    data: null,

    params: null

  }, options)

  let isGet = /^(GET|OPTIONS|HEAD|DELETE)$/i.test(options.method)

  options.params ? options.params = paramsSeralize(options.params) : null;

  options.data ? options.data = paramsSeralize(options.data) : null;

  if(isGet && options.params){

    options.url += `${options.url.indexOf('?')>=0 ? '&' : '?'}${options.params}`

  }

  let xhr = new XMLHttpRequest;

  xhr.open(options.method, options.url)

  !isGet ? xhr.setRequestHeader('Content-type','x-www-form-urlencoded') : null;

  xhr.onreadystatechange = function () {

    let { readyState, status, responseText } = xhr;

    if (/^2\d{2}/.test(status) && readyState === 4) {

      responseText = JSON.stringify(responseText)

      options.success && options.success()

    }

  }

  xhr.send(isGet ? null : options.data);

}

ajax({

  method: 'GET',

  url: '/user/list',

  data: {

    lx: 1,

    number: 2

  },

  params: {

    type: 1

  },

  success (res) {

  }

})