class Req {
  constructor({ baseURL, timeout = 6000 }) {
    let xhr = new XMLHttpRequest()
    xhr.timeout = timeout
    xhr.responseType = 'json'
    this.baseURL = baseURL
    this.xhr = xhr
  }
  async post(url, data) {
    return await new Promise((resolve, reject) => {
      this.xhr.open('POST', this.baseURL + url, true)
      this.xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
      this.xhr.onreadystatechange = ({ target }) => {
        if (target.readyState == 4 && target.status == 200) {
          resolve(target.response)
        }else if(target.status == 404){
          reject(404)
        }
      }
      this.xhr.onerror = function (e) {
        reject(e)
      }
      let str = ''
      for(let [k, v] of Object.entries(data)){
        str += `${k}=${v}&`
      }
      this.xhr.send(str)
    })
  }
}