blob和base64互转

// blob转base64
async function blobToBase64(blob) {
    let buffer = await blob.arrayBuffer()
    let bytes = new Uint8Array(buffer);
    console.log(bytes)
    // do anything with the byte array here
    let binary = ''
    var len = bytes.byteLength;
    for (var i = 0; i < len; i++) {
        binary += String.fromCharCode(bytes[i]);
    }
    base64 = 'data:image/webp;base64,' + window.btoa(binary)
    console.log(base64)
    return base64
}

// base64转blob
      function base64ToBlob(code) {
          let parts = code.split(';base64,')
          let contentType = parts[0].split(':')[1]
          let raw = window.atob(parts[1]) // 解码base64得到二进制字符串
          let rawLength = raw.length
          let uInt8Array = new Uint8Array(rawLength) // 创建8位无符号整数值的类型化数组
          for (let i = 0; i < rawLength; ++i) {
              uInt8Array[i] = raw.charCodeAt(i) // 数组接收二进制字符串
          }
          return new Blob([uInt8Array], { type: contentType })
      }