JavaScript - base64编码解码器

目录

初学js,老师交代的作业,找一串base64编码器,然后将其解码,然后就做了这个,主要就是用到bese64.js,没技术含量,望不要嘲笑。

1.初成:

QQ截图20150907215622.png

代码:

<!doctype html>
<html lang="en">
 <head>
  <meta charset="UTF-8">
  <meta name="Generator" content="EditPlus®">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <title>解密</title>
    <script type="text/javascript">
        function base64Decode(str) {
            enc64List = new Array( );
            dec64List = new Array( );
            var i;
            for (i = 0; i < 26; i++) {
                enc64List[enc64List.length] = String.fromCharCode(65 + i);
            }
            for (i = 0; i < 26; i++) {
                enc64List[enc64List.length] = String.fromCharCode(97 + i);
            }
            for (i = 0; i < 10; i++) {
                enc64List[enc64List.length] = String.fromCharCode(48 + i);
            }
            enc64List[enc64List.length] = "+";
            enc64List[enc64List.length] = "/";
            for (i = 0; i < 128; i++) {
                dec64List[dec64List.length] = -1;
            }
            for (i = 0; i < 64; i++) {
                dec64List[enc64List[i].charCodeAt(0)] = i;
            }
            var c=0, d=0, e=0, f=0, i=0, n=0;
            var input = str.split("");
            var output = "";
            var ptr = 0;
            do {
                f = input[ptr++].charCodeAt(0);
                i = dec64List[f];
                if ( f >= 0 && f < 128 && i != -1 ) {
                    if ( n % 4 == 0 ) {
                        c = i << 2;
                    } else if ( n % 4 == 1 ) {
                        c = c | ( i >> 4 );
                        d = ( i & 0x0000000F ) << 4;
                    } else if ( n % 4 == 2 ) {
                        d = d | ( i >> 2 );
                        e = ( i & 0x00000003 ) << 6;
                    } else {
                        e = e | i;
                    }
                    n++;
                    if ( n % 4 == 0 ) {
                        output += String.fromCharCode(c) + 
                                  String.fromCharCode(d) + 
                                  String.fromCharCode(e);
                    }
                }
            } while (typeof input[ptr] != "undefined");
            output += (n % 4 == 3) ? String.fromCharCode(c) + String.fromCharCode(d) : 
                      ((n % 4 == 2) ? String.fromCharCode(c) : "");
            return output;
        }
        function doDecode() {
            var src = document.getElementById('src').value;
            document.getElementById('dest').value = base64Decode(src);
        }
    </script>
 </head>
 <body>
    <p>字符:</p>
    <input type="text" name="src" style="width:99%;height:120px;" id="src" value="Nzc3PT09YXNkYXNk" />
    <input onclick="doDecode();" type="button" value="解码" name="decode" />
    <p>结果:</p>
    <input type="text" name="dest" id="dest" style="width:99%;height:120px;"></textarea>
 </body>
</html>

最后交上去说偏题了。。。。。。其实就是做多了

2.作业成品:

QQ截图20150907215919.png

没想到,这样就行了!!!!!当时我就凌乱了~

代码:

<!doctype html>
<html lang="en">
 <head>
  <meta charset="UTF-8">
  <meta name="Generator" content="EditPlus®">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <title>解密</title>
    <script type="text/javascript">
        function base64Decode(str) {
            enc64List = new Array( );
            dec64List = new Array( );
            var i;
            for (i = 0; i < 26; i++) {
                enc64List[enc64List.length] = String.fromCharCode(65 + i);
            }
            for (i = 0; i < 26; i++) {
                enc64List[enc64List.length] = String.fromCharCode(97 + i);
            }
            for (i = 0; i < 10; i++) {
                enc64List[enc64List.length] = String.fromCharCode(48 + i);
            }
            enc64List[enc64List.length] = "+";
            enc64List[enc64List.length] = "/";
            for (i = 0; i < 128; i++) {
                dec64List[dec64List.length] = -1;
            }
            for (i = 0; i < 64; i++) {
                dec64List[enc64List[i].charCodeAt(0)] = i;
            }
            var c=0, d=0, e=0, f=0, i=0, n=0;
            var input = str.split("");
            var output = "";
            var ptr = 0;
            do {
                f = input[ptr++].charCodeAt(0);
                i = dec64List[f];
                if ( f >= 0 && f < 128 && i != -1 ) {
                    if ( n % 4 == 0 ) {
                        c = i << 2;
                    } else if ( n % 4 == 1 ) {
                        c = c | ( i >> 4 );
                        d = ( i & 0x0000000F ) << 4;
                    } else if ( n % 4 == 2 ) {
                        d = d | ( i >> 2 );
                        e = ( i & 0x00000003 ) << 6;
                    } else {
                        e = e | i;
                    }
                    n++;
                    if ( n % 4 == 0 ) {
                        output += String.fromCharCode(c) + 
                                  String.fromCharCode(d) + 
                                  String.fromCharCode(e);
                    }
                }
            } while (typeof input[ptr] != "undefined");
            output += (n % 4 == 3) ? String.fromCharCode(c) + String.fromCharCode(d) : 
                      ((n % 4 == 2) ? String.fromCharCode(c) : "");
            //return output;
            alert(output);
        }

        // function doDecode() {
        //  var src = document.getElementById('src').value;
        //  document.getElementById('dest').value = base64Decode(src);
        // }
    </script>
 </head>
 <body>
    <!-- <p>字符:</p>
    <input type="text" name="src" style="width:99%;height:120px;" id="src" value="Nzc3PT09YXNkYXNk" />
    <input onclick="doDecode();" type="button" value="解码" name="decode" />
    <p>结果:</p>
    <input type="text" name="dest" id="dest" style="width:99%;height:120px;"></textarea> -->
    <input onclick="base64Decode('Nzc3PT09YXNkYXNk');" type="button" value="解码"/>
 </body>
</html>

作业完成了感觉意犹未尽,又开始优化,把加密功能、结果16进制显示都添加了,最终就成了这样。

3.最终版:

QQ截图20150907220308.png

代码:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script type="text/javascript">
        var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        var base64DecodeChars = new Array(
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
            -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
            41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);

        function base64encode(str) {
            var out, i, len;
            var c1, c2, c3;

            len = str.length;
            i = 0;
            out = "";
            while(i < len) {
            c1 = str.charCodeAt(i++) & 0xff;
            if(i == len)
            {
                out += base64EncodeChars.charAt(c1 >> 2);
                out += base64EncodeChars.charAt((c1 & 0x3) << 4);
                out += "==";
                break;
            }
            c2 = str.charCodeAt(i++);
            if(i == len)
            {
                out += base64EncodeChars.charAt(c1 >> 2);
                out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
                out += base64EncodeChars.charAt((c2 & 0xF) << 2);
                out += "=";
                break;
            }
            c3 = str.charCodeAt(i++);
            out += base64EncodeChars.charAt(c1 >> 2);
            out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));
            out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));
            out += base64EncodeChars.charAt(c3 & 0x3F);
            }
            return out;
        }

        function base64decode(str) {
            var c1, c2, c3, c4;
            var i, len, out;

            len = str.length;
            i = 0;
            out = "";
            while(i < len) {
            /* c1 */
            do {
                c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
            } while(i < len && c1 == -1);
            if(c1 == -1)
                break;

            /* c2 */
            do {
                c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
            } while(i < len && c2 == -1);
            if(c2 == -1)
                break;

            out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));

            /* c3 */
            do {
                c3 = str.charCodeAt(i++) & 0xff;
                if(c3 == 61)
                return out;
                c3 = base64DecodeChars[c3];
            } while(i < len && c3 == -1);
            if(c3 == -1)
                break;

            out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));

            /* c4 */
            do {
                c4 = str.charCodeAt(i++) & 0xff;
                if(c4 == 61)
                return out;
                c4 = base64DecodeChars[c4];
            } while(i < len && c4 == -1);
            if(c4 == -1)
                break;
            out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
            }
            return out;
        }

        function utf16to8(str) {
            var out, i, len, c;

            out = "";
            len = str.length;
            for(i = 0; i < len; i++) {
            c = str.charCodeAt(i);
            if ((c >= 0x0001) && (c <= 0x007F)) {
                out += str.charAt(i);
            } else if (c > 0x07FF) {
                out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
                out += String.fromCharCode(0x80 | ((c >>  6) & 0x3F));
                out += String.fromCharCode(0x80 | ((c >>  0) & 0x3F));
            } else {
                out += String.fromCharCode(0xC0 | ((c >>  6) & 0x1F));
                out += String.fromCharCode(0x80 | ((c >>  0) & 0x3F));
            }
            }
            return out;
        }

        function utf8to16(str) {
            var out, i, len, c;
            var char2, char3;

            out = "";
            len = str.length;
            i = 0;
            while(i < len) {
            c = str.charCodeAt(i++);
            switch(c >> 4)
            { 
              case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
                // 0xxxxxxx
                out += str.charAt(i-1);
                break;
              case 12: case 13:
                // 110x xxxx   10xx xxxx
                char2 = str.charCodeAt(i++);
                out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
                break;
              case 14:
                // 1110 xxxx  10xx xxxx  10xx xxxx
                char2 = str.charCodeAt(i++);
                char3 = str.charCodeAt(i++);
                out += String.fromCharCode(((c & 0x0F) << 12) |
                               ((char2 & 0x3F) << 6) |
                               ((char3 & 0x3F) << 0));
                break;
            }
            }

            return out;
        }

        function CharToHex(str) {
            var out, i, len, c, h;
            out = "";
            len = str.length;
            i = 0;
            while(i < len) 
            {
                c = str.charCodeAt(i++);
                h = c.toString(16);
                if(h.length < 2)
                    h = "0" + h;

                out += "\\x" + h + " ";
                if(i > 0 && i % 8 == 0)
                    out += "\r\n";
            }

            return out;
        }

        function doEncode() {
            var src = document.getElementById('src').value;
            document.getElementById('dest').value = base64encode(utf16to8(src));
        }

        function doDecode() {
            var src = document.getElementById('src').value;
            var opts = document.getElementById('opt');

            if(opts.checked)
            {
                document.getElementById('dest').value = CharToHex(base64decode(src));
            }
            else
            {
                document.getElementById('dest').value = utf8to16(base64decode(src));
            }
        }
    </script>
</head>
<body>
    <form id="form1" name="form1" method="post" action="">
    <p>请输入要进行编码或解码的字符:</p>
    <textarea name="src" id="src" cols="80" rows="6" style="width:99%;height:120px;"></textarea>
    <input onclick="doEncode();" type="button" value="编码" name="encode" />
    <input onclick="doDecode();" type="button" value="解码" name="decode" />
    <label><input type="checkbox" value="hex" name="opt" id="opt" /> 解码结果以16进制显示</label>
    </p>
    <p>Base64编码或解码结果:</p>
    <textarea name="dest" id="dest" cols="80" rows="6" style="width:99%;height:120px;"></textarea>
    </form>
</body>
</html>

标签: javascript

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