Blob 转 Base64

/**
 * Blob 转 Base64
 */
export function blobToBase64(blob: Blob): Promise<string> {
  return new Promise<string>((resolve, reject) => {
    const reader = new FileReader()
    reader.onload = () => {
      if (typeof reader.result === 'string') {
        resolve(reader.result)
      } else {
        reject(new Error('blob to base64 error'))
      }
    }
    reader.onerror = (error) => {
      reject(error)
    }
    reader.readAsDataURL(blob)
  })
}