base64轉爲圖片文件，並上傳到服務器

dataURLtoBlob = (dataurl) => {
    const arr = dataurl.split(',')
    const mime = arr[0].match(/:(.*?);/)[1]
    const bstr = atob(arr[1])
    let n = bstr.length
    const u8arr = new Uint8Array(n)
    while (n--) {
      u8arr[n] = bstr.charCodeAt(n)
    }
    return new Blob([u8arr], { type: mime })
}



postBase64 = (base64String) => {
    const form = new FormData()
    form.append('file', dataURLtoBlob(base64String), 'png')
    let url = '/common/resource/upload'
    axios.post(url, form, {
      responseType: 'json',
      withCredentials: true,
      headers: {
        'X-Requested-With': 'XMLHttpRequest',
        'Content-Type': 'multipart/form-data',
      },
    })
      .then((res) => {
        console.log(res)
      })
  }