前端根据后台返回url下载文件

前端根据后台返回url下载文件（图片、word、pdf）

    getFileAndDownload(fileName, url) {
      var x = new XMLHttpRequest()
      x.open('GET', url, true)
      x.responseType = 'blob'
      x.onload = function(e) {
        var blob = x.response
        if ('msSaveOrOpenBlob' in navigator) {
          // IE导出
          window.navigator.msSaveOrOpenBlob(blob, fileName)
        } else {
          var a = document.createElement('a')
          a.download = fileName
          a.href = URL.createObjectURL(blob)
          $('body').append(a)
          a.click()
          $(a).remove()
        }
      }
      x.send()
    },