下载文件方法

export function downloadFiles(param, callback) {
  const blob = param.type ? new Blob(['ufeff' + param.response]) : new Blob([param.response])
  if ('download' in document.createElement('a')) { // 非IE下载
    const elink = document.createElement('a')
    elink.download = param.filename
    elink.style.display = 'none'
    elink.href = param.url || window.URL.createObjectURL(blob)
    document.body.appendChild(elink)
    elink.click()
    window.URL.revokeObjectURL(elink.href) // 释放URL 对象
    document.body.removeChild(elink)
    setTimeout(function() {
      callback()
    }, 100)
  } else { // IE10+下载
    window.navigator.msSaveBlob(blob, param.filename)
    setTimeout(function() {
      callback()
    }, 100)
  }
}