微信小程序：封装wx.request方法

//baseUrl -> prefix
const fetch = (options, callback, fail) => {
  let defaultOptions = {
    url: baseUrl,
    method: 'GET',
    data: null,
    success(data) {
      if (data.statusCode === 200 && data.data.code === 200) {
        typeof callback === 'function' && callback(data.data)
      } else {
        if (typeof fail === 'function') {
          if (data.data) {
            fail(data.data.msg)
          } else {
            fail(data.errMsg)
          }
        }
      }
    },
    fail(data) {
      typeof fail === 'function' && fail(data)
    }
  }

  if(typeof options === 'string'){
     if (options.startsWith('/')){
      defaultOptions.url += options
    }else throw new Error('Illegal param.')
  }else if (typeof options === 'object') {
    defaultOptions = Object.assign(defaultOptions, options)
  }

  return wx.request(defaultOptions)
}