Base64 file, blob object, and file file object are converted to each other

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1. Convert the base64 file to a blob object:

function convertBase64UrlToBlob(urlData){
    var arr = urlData.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});
}

2. Convert the blob object to base64:

function blobToDataURL(blob, callback) {
    var a = new FileReader();
    a.onload = function (e) { callback(e.target.result); }
    a.readAsDataURL(blob);
}

3. Convert base64 to file object:

function dataURLtoFile(dataurl, filename) { //将base64转换为文件
    var 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});
}

4. Convert file to base64

  function getBase64(file: Blob) {
    return new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.readAsDataURL(file);
      reader.onload = () => resolve(reader.result);
      reader.onerror = (error) => reject(error);
    });
  }

4. Base64 file download

function (data) {
    var fileName = data.fileName;
    // 判断空
    if (util.isEmpty(fileName)) return;

    var bin = atob(data.base64.replace(/\s/g, ''));
    var buffer = new Uint8Array(bin.length);
    for (var i = 0; i < bin.length; i++) {
        buffer[i] = bin.charCodeAt(i);
    }

    var blob = new Blob([buffer.buffer], { type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' });

    // 输出文件
    if (window.navigator.msSaveBlob) {
        window.navigator.msSaveBlob(blob, fileName);
    } else {
        var a = document.createElement('a');
        a.href = URL.createObjectURL(blob);
        a.target = '_blank';
        a.download = fileName;
        a.click();
        URL.revokeObjectURL(a.href);
    }
};

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Copyright statement: This article is an original article of CSDN blogger "ChoneyLove", following the CC 4.0 BY-SA copyright agreement, please attach the original source link and this statement for reprinting .
Original link: https://blog.csdn.net/weixin_43109722/article/details/107808130