VUE3下, 如何使用base64.js ?

在VUE2下面, 可以使用以下 base64.js (标准档)
使用方法:
(先申明一下Base64 )
const Base64 = require('./base64.js').Base64; //这里这样引用一下,其它单元就直接用Base64.encode
然后就可以用了:
console.log(Base64.encode('xxxx'));
console.log(Base64.decode('eHh4eA=='));

但是,在VUE3下, 上述方法行不通. 会报错.
请问一下, 我该如何书写?

(恳请各位仁兄的指点!!!)

/*  
 *  base64.js  
 *  
 *  Licensed under the BSD 3-Clause License.  
 *    http://opensource.org/licenses/BSD-3-Clause  
 *  
 *  References:  
 *    http://en.wikipedia.org/wiki/Base64  
 */  
;  
(function(global, factory) {  
  typeof exports === 'object' && typeof module !== 'undefined' ?  
    module.exports = factory(global) :  
    typeof define === 'function' && define.amd ?  
    define(factory) : factory(global)  
}((  
  typeof self !== 'undefined' ? self :  
  typeof window !== 'undefined' ? window :  
  typeof global !== 'undefined' ? global :  
  this  
), function(global) {  
  'use strict';  
  // existing version for noConflict()  
  global = global || {};  
  var _Base64 = global.Base64;  
  var version = "2.5.1";  
  // if node.js and NOT React Native, we use Buffer  
  var buffer;  
  if (typeof module !== 'undefined' && module.exports) {  
    try {  
      buffer = eval("require('buffer').Buffer");  
    } catch (err) {  
      buffer = undefined;  
    }  
  }  
  // constants  
  var b64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';  
  var b64tab = function(bin) {  
    var t = {};  
    for (var i = 0, l = bin.length; i < l; i++) t[bin.charAt(i)] = i;  
    return t;  
  }(b64chars);  
  var fromCharCode = String.fromCharCode;  
  // encoder stuff  
  var cb_utob = function(c) {  
    if (c.length < 2) {  
      var cc = c.charCodeAt(0);  
      return cc < 0x80 ? c :  
        cc < 0x800 ? (fromCharCode(0xc0 | (cc >>> 6)) +  
          fromCharCode(0x80 | (cc & 0x3f))) :  
        (fromCharCode(0xe0 | ((cc >>> 12) & 0x0f)) +  
          fromCharCode(0x80 | ((cc >>> 6) & 0x3f)) +  
          fromCharCode(0x80 | (cc & 0x3f)));  
    } else {  
      var cc = 0x10000 +  
        (c.charCodeAt(0) - 0xD800) * 0x400 +  
        (c.charCodeAt(1) - 0xDC00);  
      return (fromCharCode(0xf0 | ((cc >>> 18) & 0x07)) +  
        fromCharCode(0x80 | ((cc >>> 12) & 0x3f)) +  
        fromCharCode(0x80 | ((cc >>> 6) & 0x3f)) +  
        fromCharCode(0x80 | (cc & 0x3f)));  
    }  
  };  
  var re_utob = /[\uD800-\uDBFF][\uDC00-\uDFFFF]|[^\x00-\x7F]/g;  
  var utob = function(u) {  
    return u.replace(re_utob, cb_utob);  
  };  
  var cb_encode = function(ccc) {  
    var padlen = [0, 2, 1][ccc.length % 3],  
      ord = ccc.charCodeAt(0) << 16 |  
      ((ccc.length > 1 ? ccc.charCodeAt(1) : 0) << 8) |  
      ((ccc.length > 2 ? ccc.charCodeAt(2) : 0)),  
      chars = [  
        b64chars.charAt(ord >>> 18),  
        b64chars.charAt((ord >>> 12) & 63),  
        padlen >= 2 ? '=' : b64chars.charAt((ord >>> 6) & 63),  
        padlen >= 1 ? '=' : b64chars.charAt(ord & 63)  
      ];  
    return chars.join('');  
  };  

  var btoa = global.btoa ? function(b) {  
    return global.btoa(b);  
  } : function(b) {  
    return b.replace(/[\s\S]{1,3}/g, cb_encode);  
  };  
  var _encode = buffer ?  
    buffer.from && Uint8Array && buffer.from !== Uint8Array.from ?  
    function(u) {  
      return (u.constructor === buffer.constructor ? u : buffer.from(u))  
        .toString('base64')  
    } :  
    function(u) {  
      return (u.constructor === buffer.constructor ? u : new buffer(u))  
        .toString('base64')  
    } :  
    function(u) {  
      return btoa(utob(u))  
    };  
  var encode = function(u, urisafe) {  
    return !urisafe ?  
      _encode(String(u)) :  
      _encode(String(u)).replace(/[+\/]/g, function(m0) {  
        return m0 == '+' ? '-' : '_';  
      }).replace(/=/g, '');  
  };  
  var encodeURI = function(u) {  
    return encode(u, true)  
  };  
  // decoder stuff  
  var re_btou = new RegExp([  
    '[\xC0-\xDF][\x80-\xBF]',  
    '[\xE0-\xEF][\x80-\xBF]{2}',  
    '[\xF0-\xF7][\x80-\xBF]{3}'  
  ].join('|'), 'g');  
  var cb_btou = function(cccc) {  
    switch (cccc.length) {  
      case 4:  
        var cp = ((0x07 & cccc.charCodeAt(0)) << 18) |  
          ((0x3f & cccc.charCodeAt(1)) << 12) |  
          ((0x3f & cccc.charCodeAt(2)) << 6) |  
          (0x3f & cccc.charCodeAt(3)),  
          offset = cp - 0x10000;  
        return (fromCharCode((offset >>> 10) + 0xD800) +  
          fromCharCode((offset & 0x3FF) + 0xDC00));  
      case 3:  
        return fromCharCode(  
          ((0x0f & cccc.charCodeAt(0)) << 12) |  
          ((0x3f & cccc.charCodeAt(1)) << 6) |  
          (0x3f & cccc.charCodeAt(2))  
        );  
      default:  
        return fromCharCode(  
          ((0x1f & cccc.charCodeAt(0)) << 6) |  
          (0x3f & cccc.charCodeAt(1))  
        );  
    }  
  };  
  var btou = function(b) {  
    return b.replace(re_btou, cb_btou);  
  };  
  var cb_decode = function(cccc) {  
    var len = cccc.length,  
      padlen = len % 4,  
      n = (len > 0 ? b64tab[cccc.charAt(0)] << 18 : 0) |  
      (len > 1 ? b64tab[cccc.charAt(1)] << 12 : 0) |  
      (len > 2 ? b64tab[cccc.charAt(2)] << 6 : 0) |  
      (len > 3 ? b64tab[cccc.charAt(3)] : 0),  
      chars = [  
        fromCharCode(n >>> 16),  
        fromCharCode((n >>> 8) & 0xff),  
        fromCharCode(n & 0xff)  
      ];  
    chars.length -= [0, 0, 2, 1][padlen];  
    return chars.join('');  
  };  
  var _atob = global.atob ? function(a) {  
    return global.atob(a);  
  } : function(a) {  
    return a.replace(/\S{1,4}/g, cb_decode);  
  };  
  var atob = function(a) {  
    return _atob(String(a).replace(/[^A-Za-z0-9\+\/]/g, ''));  
  };  
  var _decode = buffer ?  
    buffer.from && Uint8Array && buffer.from !== Uint8Array.from ?  
    function(a) {  
      return (a.constructor === buffer.constructor ?  
        a : buffer.from(a, 'base64')).toString();  
    } :  
    function(a) {  
      return (a.constructor === buffer.constructor ?  
        a : new buffer(a, 'base64')).toString();  
    } :  
    function(a) {  
      return btou(_atob(a))  
    };  
  var decode = function(a) {  
    return _decode(  
      String(a).replace(/[-_]/g, function(m0) {  
        return m0 == '-' ? '+' : '/'  
      })  
      .replace(/[^A-Za-z0-9\+\/]/g, '')  
    );  
  };  
  var noConflict = function() {  
    var Base64 = global.Base64;  
    global.Base64 = _Base64;  
    return Base64;  
  };  
  // export Base64  
  global.Base64 = {  
    VERSION: version,  
    atob: atob,  
    btoa: btoa,  
    fromBase64: decode,  
    toBase64: encode,  
    utob: utob,  
    encode: encode,  
    encodeURI: encodeURI,  
    btou: btou,  
    decode: decode,  
    noConflict: noConflict,  
    __buffer__: buffer  
  };  
  // if ES5 is available, make Base64.extendString() available  
  if (typeof Object.defineProperty === 'function') {  
    var noEnum = function(v) {  
      return {  
        value: v,  
        enumerable: false,  
        writable: true,  
        configurable: true  
      };  
    };  
    global.Base64.extendString = function() {  
      Object.defineProperty(  
        String.prototype, 'fromBase64', noEnum(function() {  
          return decode(this)  
        }));  
      Object.defineProperty(  
        String.prototype, 'toBase64', noEnum(function(urisafe) {  
          return encode(this, urisafe)  
        }));  
      Object.defineProperty(  
        String.prototype, 'toBase64URI', noEnum(function() {  
          return encode(this, true)  
        }));  
    };  
  }  
  //  
  // export Base64 to the namespace  
  //  
  if (global['Meteor']) { // Meteor.js  
    Base64 = global.Base64;  
  }  
  // module.exports and AMD are mutually exclusive.  
  // module.exports has precedence.  
  if (typeof module !== 'undefined' && module.exports) {  
    module.exports.Base64 = global.Base64;  
  } else if (typeof define === 'function' && define.amd) {  
    // AMD. Register as an anonymous module.  
    define([], function() {  
      return global.Base64  
    });  
  }  
  // that's it!  
  return {  
    Base64: global.Base64  
  }  
}));