ajax 文件下载

/**

• ajax 文件下载
• @param {Object} config 下载的文件配置 url、timeout、callback
• 返回请求成功或失败
  */

export function fileDownload (config) {
  var xhr = new XMLHttpRequest()
  var dataPath = config.url
  xhr.open('GET', dataPath)
  // xhr.onprogress = function (event) {
  //   console.log(event)
  //   //   console.log(Math.round((event.loaded / event.total) * 100) + '%')
  // }
  xhr.responseType = 'arraybuffer'
  xhr.timeout = config.timeout || 1 * 60 * 1000
  xhr.addEventListener('readystatechange', function (event) {
    // console.log(event)
    if (xhr.status === 200 && xhr.readyState === 4) {
      var contentDisposition = xhr.getResponseHeader('Content-disposition')
      var contentType = xhr.getResponseHeader('Content-type')
      var blob = new Blob([xhr.response], {
        type: contentType
      })
      var url = window.URL.createObjectURL(blob)
      var regex = /filename=[^;]*/
      var matchs = contentDisposition.match(regex)
      var filename = ''
      if (matchs) {
        filename = decodeURIComponent(matchs[0].split('=')[1])
      } else {
        filename = +Date.now() + '.xlsx'
      }
      var a = document.createElement('a')
      a.href = url
      a.download = filename
      a.click()
      window.URL.revokeObjectURL(url)
      config.callBack && config.callBack(true)
    }
  })
  xhr.ontimeout = function () {
    // console.log('timeout...')
    config.callBack && config.callBack(false)
  }
  xhr.withCredentials = true
  xhr.send()
}