base64 轉 File

1.通過new File()將base64轉換成file文件，此方式需考慮瀏覽器兼容問題。

// 將base64轉換為文件
function dataURLtoFile(dataurl, filename) {
  let arr = dataurl.split(","),
    mime = arr[0].match(/:(.*?);/)[1],
    bstr = atob(arr[1]),
    n = bstr.length,
    u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  return new File([u8arr], filename, { type: mime });
}

//調用
let file = dataURLtoFile(base64Data, imgName);

2.先將base64轉換成blob，再將blob轉換成file文件，此方法不存在瀏覽器不兼容問題。

// 將base64轉換為blob
function dataURLtoBlob(dataurl) {
  let arr = dataurl.split(","),
    mime = arr[0].match(/:(.*?);/)[1],
    bstr = atob(arr[1]),
    n = bstr.length,
    u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  return new Blob([u8arr], { type: mime });
}
// 將blob轉換為file
function blobToFile(theBlob, fileName) {
  theBlob.lastModifiedDate = new Date();
  theBlob.name = fileName;
  return theBlob;
}
// 調用
let blob = dataURLtoBlob(base64Data);
let file = blobToFile(blob, imgName);

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