file文件转blob

// file文件转换为blob

export const fileToBlob = (file) => {

  return new Promise(resolve => {

    let reader = new FileReader()

    reader.readAsArrayBuffer(file)

    let blob = null;

    reader.onload = (e) => {

      if (typeof e.target.result === 'object') {

        blob = new Blob([e.target.result])

      } else {

        blob = e.target.result

      }

      resolve(blob)

    }

  })

}