1 function Base64() {

  2   // private property

  3   _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

  4   // 公共编码方法

  5   this.encode = function (input) {

  6     var output = "";

  7     var chr1, chr2, chr3, enc1, enc2, enc3, enc4;

  8     var i = 0;

  9     input = _utf8_encode(input);

 10     while (i < input.length) {

 11       chr1 = input.charCodeAt(i++);

 12       chr2 = input.charCodeAt(i++);

 13       chr3 = input.charCodeAt(i++);

 14       enc1 = chr1 >> 2;

 15       enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);

 16       enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);

 17       enc4 = chr3 & 63;

 18       if (isNaN(chr2)) {

 19           enc3 = enc4 = 64;

 20       } else if (isNaN(chr3)) {

 21           enc4 = 64;

 22       }

 23       output = output +

 24       _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +

 25       _keyStr.charAt(enc3) + _keyStr.charAt(enc4);

 26     }

 27     return output;

 28   }

 29

 30   // 公共解码方法

 31   this.decode = function (input) {

 32     var output = "";

 33     var chr1, chr2, chr3;

 34     var enc1, enc2, enc3, enc4;

 35     var i = 0;

 36     input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

 37     while (i < input.length) {

 38       enc1 = _keyStr.indexOf(input.charAt(i++));

 39       enc2 = _keyStr.indexOf(input.charAt(i++));

 40       enc3 = _keyStr.indexOf(input.charAt(i++));

 41       enc4 = _keyStr.indexOf(input.charAt(i++));

 42       chr1 = (enc1 << 2) | (enc2 >> 4);

 43       chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);

 44       chr3 = ((enc3 & 3) << 6) | enc4;

 45       output = output + String.fromCharCode(chr1);

 46       if (enc3 != 64) {

 47         output = output + String.fromCharCode(chr2);

 48       }

 49       if (enc4 != 64) {

 50         output = output + String.fromCharCode(chr3);

 51       }

 52     }

 53     output = _utf8_decode(output);

 54     return output;

 55   }

 56

 57   // UTF-8编码的私有方法

 58   _utf8_encode = function (string) {

 59     string = string.replace(/\r\n/g,"\n");

 60     var utftext = "";

 61     for (var n = 0; n < string.length; n++) {

 62       var c = string.charCodeAt(n);

 63       if (c < 128) {

 64         utftext += String.fromCharCode(c);

 65       } else if((c > 127) && (c < 2048)) {

 66         utftext += String.fromCharCode((c >> 6) | 192);

 67         utftext += String.fromCharCode((c & 63) | 128);

 68       } else {

 69         utftext += String.fromCharCode((c >> 12) | 224);

 70         utftext += String.fromCharCode(((c >> 6) & 63) | 128);

 71         utftext += String.fromCharCode((c & 63) | 128);

 72       }

 73     }

 74     return utftext;

 75   }

 76

 77   // UTF-8解码的私有方法

 78   _utf8_decode = function (utftext) {

 79     var string = "";

 80     var i = 0;

 81     var c = c1 = c2 = 0;

 82     while ( i < utftext.length ) {

 83       c = utftext.charCodeAt(i);

 84       if (c < 128) {

 85         string += String.fromCharCode(c);

 86         i++;

 87       } else if((c > 191) && (c < 224)) {

 88         c2 = utftext.charCodeAt(i+1);

 89         string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));

 90         i += 2;

 91       } else {

 92         c2 = utftext.charCodeAt(i+1);

 93         c3 = utftext.charCodeAt(i+2);

 94         string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));

 95         i += 3;

 96       }

 97     }

 98     return string;

 99   }

100 }

加密解密方法使用：

1.加密

var str = '码云笔记mybj123';

var base = new Base64();

var result = base.encode(str);

//document.write(result);

2. 解密

var result2 = base.decode(result);

document.write(result2);