JS implementation Base64_encode and Base64_decode (instance code)

JS implementation Base64_encode and Base64_decode (instance code) _javascript skills

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Base64 is a representation that represents binary data based on 64 printable characters. Because 2 of the 6 times equals 64, each 6 bit is a unit, corresponding to a printable character. Three bytes have 24 bits, corresponding to 4 Base64 units, that is, 3 bytes need to be represented by 4 printable characters. It can be used as a transport encoding for e-mail messages. printable characters in Base64 include letters A-Z, a-Z, number 0-9, 62 characters in total, and two printable symbols in different systems (this class library uses ' + ', '/' these two characters). Some other coding methods, such as Uuencode, and later versions of BinHex use different 64 character sets to represent 6 binary digits, but they are not called Base64.
Base64 is often used to represent, transmit, and store binary data in situations where text data is normally processed. Includes MIME-Email,email via MIME, which stores complex data in XML.
Base64 is actually a simple method of permutation encryption, but the usefulness of BASE64 is often not to prevent information leakage, and in order to facilitate transmission, the BASE64 encoded information will be longer than the original information, about 4/3 times times.

Implementation code One, test can be used

var&nbsp;base64encodechars&nbsp;=&nbsp; "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789+/"; Var&nbsp;base64decodechars&nbsp;=&nbsp;new&nbsp;array ( -1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1 , &nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1, &nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1, &nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1, &NBSP;62,&NBSP;-1,&NBSP;-1,&NBSP;-1,&NBSP;63,&NBSP;52,&NBSP;53,&NBSP;54,&NBSP;55,&NBSP;56,&NBSP;57,&NBSP;58, &nbsp;59,&nbsp;60,&nbsp;61,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;-1,&nbsp;0,&nbsp;1, &NBSP;2,&NBSP;3,&NBSP;4,&NBSP;5,&NBSP;6,&NBSP;7,&NBSP;8,&NBSP;9,&NBSP;10,&NBSP;11,&NBSP;12,&NBSP;13,&NBSP;14, &nbsp;15,&nbsp;16,&nbsp;17,&nbsp;18,&nbsp;19,&nbsp;20,&nbsp;21,&nbsp;22,&nbsp;23,&nbsp;24,&nbsp;25,&nbsp;-1, &nbsp;-1,&nbsp;-1,&nbsp;-1, &nbsp;-1,&nbsp;-1,&nbsp;26,&nbsp;27,&nbsp;28,&nbsp;29,&nbsp;30,&nbsp;31,&nbsp;32,&nbsp;33,&nbsp;34,&nbsp;35, &NBSP;36,&NBSP;37,&NBSP;38,&NBSP;39,&NBSP;40,&NBSP;41,&NBSP;42,&NBSP;43,&NBSP;44,&NBSP;45,&NBSP;46,&NBSP;47,
&NBSP;48,&NBSP;49,&NBSP;50,&NBSP;51,&NBSP;-1,&NBSP;-1,&NBSP;-1,&NBSP;-1,&NBSP;-1);
/** &nbsp;*&nbsp;base64 Code &nbsp;*&nbsp; @param &nbsp;{object}&nbsp;str &nbsp;*/function&nbsp;base64encode (str) {
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;out,&nbsp;i,&nbsp;len;
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;c1,&nbsp;c2,&nbsp;c3;
&nbsp;&nbsp;&nbsp;&nbsp;len&nbsp;=&nbsp;str.length;
&nbsp;&nbsp;&nbsp;&nbsp;i&nbsp;=&nbsp;0;
&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;=&nbsp; ""; &nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (I&nbsp;&lt;&nbsp;len) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;c1&nbsp;=&nbsp;str.charcodeat (i++) &nbsp;&amp;&nbsp;0xff; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (I&nbsp;==&nbsp;len) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsP;base64encodechars.charat (C1&NBSP;&GT;&GT;&NBSP;2); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;
Base64encodechars.charat ((c1&nbsp;&amp;&nbsp;0x3) &nbsp;&lt;&lt;&nbsp;4);
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp; "= =";
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c2&nbsp;=
&nbsp;str.charcodeat (i++); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (I&nbsp;==&nbsp;len) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;base64encodechars.charat (c1&nbsp;&gt;&gt;
&NBSP;2); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp; Base64encodechars.charat ((c1&nbsp;&amp;&nbsp;0x3) &nbsp;&lt;&lt;&nbsp;4) &nbsp;|&nbsp; ((c2&nbsp;&amp;&nbsp;0xf0
) (&nbsp;&gt;&gt;&nbsp;4)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsP;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;base64encodechars.charat ((C2&nbsp;&amp;&nbsp;0xF)
&NBSP;&LT;&LT;&NBSP;2);
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp; "=";
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c3&nbsp;=
&nbsp;str.charcodeat (i++); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;base64encodechars.charat (c1&nbsp;&gt;&gt;
&NBSP;2); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;base64encodechars.charat ((c1&nbsp;&amp;
&NBSP;0X3) &nbsp;&lt;&lt;&nbsp;4) &nbsp;|&nbsp; ((c2&nbsp;&amp;&nbsp;0xf0) &nbsp;&gt;&gt;&nbsp;4)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;base64encodechars.charat ((c2&nbsp;&amp;
&NBSP;0XF) &nbsp;&lt;&lt;&nbsp;2) &nbsp;|&nbsp; ((c3&nbsp;&amp;&nbsp;0xc0) &nbsp;&gt;&gt;&nbsp;6)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;out&nbsp;+=&nbsp;base64encodechars.charat (c3&nbsp;&amp;&nbsp;0x3f);
&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;out;
/** &nbsp;*&nbsp;base64 decoding &nbsp;*&nbsp; @param &nbsp;{object}&nbsp;str &nbsp;*/function&nbsp;base64decode (str) {
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;c1,&nbsp;c2,&nbsp;c3,&nbsp;c4;
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;i,&nbsp;len,&nbsp;out;
&nbsp;&nbsp;&nbsp;&nbsp;len&nbsp;=&nbsp;str.length;
&nbsp;&nbsp;&nbsp;&nbsp;i&nbsp;=&nbsp;0;
&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;=&nbsp; ""; &nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (I&nbsp;&lt;&nbsp;len) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;/*&nbsp;c1&nbsp;*/&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;do&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c1&nbsp;=&nbsp;base64decodechars[str.charcodeat (i++) &nbsp;
&amp;&nbsp;0xff]; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (i &nbsp;&lt;&nbsp;len&nbsp;&amp;&amp;&nbsP;C1&NBSP;==&NBSP;-1); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c1&nbsp;==&nbsp;-1) &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;c2&nbsp;*/&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;do&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c2&nbsp;=&nbsp;
Base64decodechars[str.charcodeat (i++) &nbsp;&amp;&nbsp;0xff]; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (i
&NBSP;&LT;&NBSP;LEN&NBSP;&AMP;&AMP;&NBSP;C2&NBSP;==&NBSP;-1); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c2&nbsp;==&nbsp;-1) &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;string.fromcharcode ((C1&NBSP;&LT;&LT;&NBSP;2)
&nbsp;|&nbsp; ((c2&nbsp;&amp;&nbsp;0x30) &nbsp;&gt;&gt;&nbsp;4)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;c3&nbsp;*/&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;do&nbsp;{&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c3&nbsp;=&nbsp;str.charcodeat (i++) &nbsp;&amp;&nbsp;0xff;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c3&nbsp;==&nbsp;61) &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;
Out
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c3&nbsp;=&nbsp;base64DecodeChars[c3]; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (i
&NBSP;&LT;&NBSP;LEN&NBSP;&AMP;&AMP;&NBSP;C3&NBSP;==&NBSP;-1); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c3&nbsp;==&nbsp;-1) &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;string.fromcharcode ((C2&nbsp;&amp;&nbsp;0XF) &nbsP;&LT;&LT;&NBSP;4) &nbsp;|&nbsp; ((c3&nbsp;&amp;&nbsp;0x3c) &nbsp;&gt;&gt;&nbsp;2)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;c4&nbsp;*/&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;do&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c4&nbsp;=&nbsp;
Str.charcodeat (i++) &nbsp;&amp;&nbsp;0xff;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c4&nbsp;==&nbsp;61) &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;
Out
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c4&nbsp;=&nbsp;base64DecodeChars[c4]; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (i
&NBSP;&LT;&NBSP;LEN&NBSP;&AMP;&AMP;&NBSP;C4&NBSP;==&NBSP;-1); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c4&nbsp;==&nbsp;-1) &nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;string.fromcharcode ((c3&nbsp;&amp;&nbsp;0x03
) (&nbsp;&lt;&lt;&nbsp;6) &nbsp;|&nbsp;c4);
&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;out;
/** &nbsp;*&nbsp;utf16 ext. UTF8 &nbsp;*&nbsp; @param &nbsp;{object}&nbsp;str &nbsp;*/function&nbsp;utf16to8 (str) {
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;out,&nbsp;i,&nbsp;len,&nbsp;c;
&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;=&nbsp; "";
&nbsp;&nbsp;&nbsp;&nbsp;len&nbsp;=&nbsp;str.length; &nbsp;&nbsp;&nbsp;&nbsp;for&nbsp; (i&nbsp;=&nbsp;0;&nbsp;i&nbsp;&lt;&nbsp;len;&nbsp;i++) &nbsp;{&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;c&nbsp;=&nbsp;str.charcodeat (i); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; ((c&nbsp;&gt;=&nbsp;0x0001) &nbsp;&amp;&amp;&nbsp; (c &nbsp;&lt;=&nbsp;0x007f)) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out
&nbsp;+=&nbsp;str.charat (i); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;else&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp; (c&nbsp;&gt; &NBSP;0X07FF) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;out&nbsp;+=&nbsp;string.fromcharcode (0xe0&nbsp;|&nbsp; (c&nbsp;&gt;&gt;&nbsp;12) &nbsp;&amp;&nbsp;0x0F)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=
&nbsp;string.fromcharcode (0x80&nbsp;|&nbsp; (c&nbsp;&gt;&gt;&nbsp;6) &nbsp;&amp;&nbsp;0x3f)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=
&nbsp;string.fromcharcode (0x80&nbsp;|&nbsp; (c&nbsp;&gt;&gt;&nbsp;0) &nbsp;&amp;&nbsp;0x3f)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;else&nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nBsp
String.fromCharCode (0xc0&nbsp;|&nbsp; (c&nbsp;&gt;&gt;&nbsp;6) &nbsp;&amp;&nbsp;0x1f)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=
&nbsp;string.fromcharcode (0x80&nbsp;|&nbsp; (c&nbsp;&gt;&gt;&nbsp;0) &nbsp;&amp;&nbsp;0x3f)); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;
&nbsp;&nbsp;return&nbsp;out;
/** &nbsp;*&nbsp;utf8 ext. utf16 &nbsp;*&nbsp; @param &nbsp;{object}&nbsp;str &nbsp;*/function&nbsp;utf8to16 (str) {
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;out,&nbsp;i,&nbsp;len,&nbsp;c;
&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;char2,&nbsp;char3;
&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;=&nbsp; "";
&nbsp;&nbsp;&nbsp;&nbsp;len&nbsp;=&nbsp;str.length;
&nbsp;&nbsp;&nbsp;&nbsp;i&nbsp;=&nbsp;0; &nbsp;&nbsp;&nbsp;&nbsp;while&nbsp; (I&nbsp;&lt;&nbsp;len) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;c&nbsp;=&nbsp;str.charcodeat (i++); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;switch&nBSP; (c&nbsp;&gt;&gt;&nbsp;4) &nbsp;{&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Case&nbsp;0: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;case&nbsp;1: &nbsp;&nbsp; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;CASE&NBSP;2: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;case&nbsp;3: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;case&nbsp;4: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;case&nbsp;5: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;case&nbsp;6: &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;case&nbsp;7: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;0xxxxxxx &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+=&nbsp;str.charat (i&nbsp;-&nbsp;1); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;CASE&NBSP;12: &nbsp;&nbsp;&nbsp;&nbsp; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;CASE&NBSP;13: &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;110x&nbsp;xxxx&nbsp;10xx&nbsp;xxxx &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;char2&nbsp;=&nbsp;str.charcodeat
(i++); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+= &nbsp;string.fromcharcode ((c&nbsp;&amp;&nbsp;0x1f) &nbsp;&lt;&lt;&nbsp;6) &nbsp;|&nbsp; (char2&nbsp;&amp;&nbsp;
0x3F));
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;CASE&NBSP;14: &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&Nbsp;&nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;1110&nbsp;xxxx10xx&nbsp;xxxx10xx&nbsp;xxxx &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;char2&nbsp;=&nbsp;str.charcodeat (i++); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;char3&nbsp;=
&nbsp;str.charcodeat (i++); &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;out&nbsp;+= &nbsp;string.fromcharcode ((c&nbsp;&amp;&nbsp;0x0f) &nbsp;&lt;&lt;&nbsp;12) &nbsp;|&nbsp; ((char2&nbsp;&amp;
&nbsp;0x3f) &nbsp;&lt;&lt;&nbsp;6) &nbsp;|&nbsp; ((char3&nbsp;&amp;&nbsp;0x3f) &nbsp;&lt;&lt;&nbsp;0));
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;break; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;} &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;
Out }//demo//function&nbsp;doit () {//&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;f&nbsp;=&nbsp;document.f;//&nbsp;&nbsp;&nbsp; &nbsP;f.output.value&nbsp;=&nbsp;base64encode (Utf16to8 (F.source.value));
&nbsp;&nbsp;&nbsp;&nbsp;f.decode.value&nbsp;=&nbsp;utf8to16 (Base64decode (F.output.value)); //}

Functional split version, that is, two JS functions are written out separately

JavaScript base64 cryptographic functions and Base64 decryption functions, imitation PHP base64_encode () and Base64_decode (). Attached examples. You can save the JS code to base64.js and call it when needed.
Note: Base64 encryption and decryption are solid, please do not change the following code, or you may cause a program error, or can not get the correct results.
To ensure the correctness of the code, please download the attachment base64.js (no instances) and do not copy the page code directly.

Base64 Encryption Code

    function Base64_encode (str) {var c1, C2, C3;        
        var base64encodechars = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789+/";

        var i = 0, len= str.length, string = ';
            while (I &lt; len) {c1 = Str.charcodeat (i++) &amp; 0xFF;
                if (i = = len) {string + Base64encodechars.charat (C1 &gt;&gt; 2);
                string + = Base64encodechars.charat ((C1 &amp; 0x3) &lt;&lt; 4);
                string + = "= =";
            Break
            } C2 = Str.charcodeat (i++);
                if (i = = len) {string + Base64encodechars.charat (C1 &gt;&gt; 2); String + Base64encodechars.charat ((C1 &amp; 0x3) &lt;&lt; 4) |
                ((C2 &amp; 0xF0) &gt;&gt; 4));
                string + = Base64encodechars.charat ((C2 &amp; 0xF) &lt;&lt; 2);
                string + = "=";
            Break
            } C3 = Str.charcodeat (i++); string + = Base64encodechArs.charat (C1 &gt;&gt; 2); String + Base64encodechars.charat ((C1 &amp; 0x3) &lt;&lt; 4) |
            ((C2 &amp; 0xF0) &gt;&gt; 4)); String + Base64encodechars.charat ((C2 &amp; 0xF) &lt;&lt; 2) |
            ((C3 &amp; 0xc0) &gt;&gt; 6)); string + = Base64encodechars.charat (C3 &amp; 0x3F)} return string}

Base64 decryption, code

function Base64_decode (str) {var c1, C2, C3, C4;
            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
            2,-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, 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);

        var i=0, Len = str.length, string = '; while (I &lt; len) {do{C1 = base64decodechars[str.charcodeat (i++) &amp; 0xFF]} w

            Hile (i &lt; len &amp;&amp; C1 = = 1);

        if (C1 = = 1) break;    do{C2 = base64decodechars[str.charcodeat (i++) &amp; 0xFF]} while (i) ;

            Len &amp;&amp; c2 =-1);

            if (C2 = = 1) break; String + string.fromcharcode (C1 &lt;&lt; 2) |

            ((C2 &amp; 0x30) &gt;&gt; 4));
                do{C3 = Str.charcodeat (i++) &amp; 0xFF;

                if (C3 = =) return string;

            C3 = Base64decodechars[c3]} while (I &lt; Len &amp;&amp; C3 = = 1);

            if (C3 = = 1) break; String + String.fromCharCode ((C2 &amp; 0XF) &lt;&lt; 4) |

            ((C3 &amp; 0x3c) &gt;&gt; 2));
                do{C4 = str.charcodeat (i++) &amp; 0xFF;
                if (C4 = =) return string;

            C4 = base64decodechars[c4]} while (I &lt; len &amp;&amp; C4 = = 1);

            if (C4 = = 1) break; string + = String.fromCharCode ((C3 &amp; 0x03) &lt;&lt; 6) | c4)} return string; }

Test code for the code above

 document.write (Base64_encode (' www.jb51.net '));
    document.write (' <br/> ');

Implementation code two: for UTF8

&lt;script language= ' JavaScript ' &gt;/* utf.js-utf-8 &lt;=&gt; UTF-16 convertion * Copyright (C) 1999 Masanao & lt;iz@onicos.co.jp&gt; * version:1.0 * LASTMODIFIED:DEC 1999 * This library are free.
You can redistribute it and/or modify it.
* * * Interfaces: * UTF8 = Utf16to8 (UTF16);
* utf16 = Utf16to8 (UTF8);

  */function Utf16to8 (str) {var out, I, Len, C;
  out = "";
  len = str.length;
   for (i = 0; i &lt; len; i++) {c = str.charcodeat (i);
   if ((c &gt;= 0x0001) &amp;&amp; (c &lt;= 0x007f)) {out = = Str.charat (i); else if (C &gt; 0x07ff) {out + = String.fromCharCode (0xe0 |
    ((c &gt;&gt;) &amp; 0x0f)); Out + + string.fromcharcode (0x80 |
    ((c &gt;&gt; 6) &amp; 0x3F)); Out + + string.fromcharcode (0x80 |
   ((c &gt;&gt; 0) &amp; 0x3F)); else {out = = String.fromCharCode (0xc0 |
    ((c &gt;&gt; 6) &amp; 0x1F)); Out + + string.fromcharcode (0x80 |
   ((c &gt;&gt; 0) &amp; 0x3F));
} return out; function Utf8to16 (str) {var out, I, lEn, C;

  var char2, Char3;
  out = "";
  len = str.length;
  i = 0;
   while (I &lt; len) {c = str.charcodeat (i++); Switch (c &gt;&gt; 4) {case 0:case 1:case 2:case 3:case 4:case 5:case 6:case 7://0xxxxxxx out = = S
    Tr.charat (i-1);
   Break
    Case 12:case://110x xxxx 10xx xxxx char2 = str.charcodeat (i++); Out + + String.fromCharCode ((C &amp; 0x1F) &lt;&lt; 6) |
    (Char2 &amp; 0x3F));
   Break
    Case://1110 xxxx 10xx xxxx 10xx xxxx char2 = str.charcodeat (i++);
    CHAR3 = Str.charcodeat (i++);
           Out + + String.fromCharCode ((C &amp; 0x0f) &lt;&lt; 12) |
           ((Char2 &amp; 0x3F) &lt;&lt; 6) |
    ((Char3 &amp; 0x3F) &lt;&lt; 0));
   Break
} return out; }/* Copyright (C) 1999 Masanao Izumo &lt;iz@onicos.co.jp&gt; * version:1.0 * LASTMODIFIED:DEC 1999 * This library I s free.
You can redistribute it and/or modify it.
* * * Interfaces: * b64 = base64encode (data);
* data = Base64decode (B64);

*/
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, 62,-1, 1, 1, 63, 52 4, 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, 1
  7, 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,

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 &lt; len) {c1 = Str.charcodeat (i++) &amp; 0xFF;
    if (i = = len) {out + = Base64encodechars.charat (C1 &gt;&gt; 2);
    Out + = Base64encodechars.charat ((C1 &amp; 0x3) &lt;&lt; 4);
    Out + = "= =";
   Break } c2 = str.charCodeAt (i++);
    if (i = = len) {out + = Base64encodechars.charat (C1 &gt;&gt; 2); Out + + Base64encodechars.charat ((C1 &amp; 0x3) &lt;&lt; 4) |
    ((C2 &amp; 0xF0) &gt;&gt; 4));
    Out + = Base64encodechars.charat ((C2 &amp; 0xF) &lt;&lt; 2);
    Out + = "=";
   Break
   } C3 = Str.charcodeat (i++);
   Out + = Base64encodechars.charat (C1 &gt;&gt; 2); Out + + Base64encodechars.charat ((C1 &amp; 0x3) &lt;&lt; 4) |
   ((C2 &amp; 0xF0) &gt;&gt; 4)); Out + + Base64encodechars.charat ((C2 &amp; 0xF) &lt;&lt; 2) |
   ((C3 &amp; 0xc0) &gt;&gt;6));
  Out + = Base64encodechars.charat (C3 &amp; 0x3F);
} return out;
  function Base64decode (str) {var c1, C2, C3, C4;

  var i, Len, out;
  len = str.length;
  i = 0;
  out = "";
   while (I &lt; len) {/* C1 */do {c1 = Base64decodechars[str.charcodeat (i++) &amp; 0xFF];
   while (I &lt; len &amp;&amp; C1 = = 1);

   if (C1 = = 1) break;
   /* C2/do {c2 = Base64decodechars[str.charcodeat (i++) &amp; 0xFF]; } while(I &lt; len &amp;&amp; C2 = = 1);

   if (C2 = = 1) break; Out + + string.fromcharcode (C1 &lt;&lt; 2) |

   ((C2 &amp; 0x30) &gt;&gt; 4));
    /* C3/Do {c3 = Str.charcodeat (i++) &amp; 0xFF;
    if (C3 = =) return out;
   C3 = Base64decodechars[c3];
   while (I &lt; Len &amp;&amp; C3 = = 1);

   if (C3 = = 1) break; Out + + String.fromCharCode ((C2 &amp; 0XF) &lt;&lt; 4) |

   ((C3 &amp; 0x3c) &gt;&gt; 2));
    /* C4/do {c4 = str.charcodeat (i++) &amp; 0xFF;
    if (C4 = =) return out;
   C4 = base64decodechars[c4];
   while (i &lt; len &amp;&amp; C4 = = 1);
   if (C4 = = 1) break;
  Out + = String.fromCharCode ((C3 &amp; 0x03) &lt;&lt; 6) | c4);
} return out;
 }//input base64 encode function Strdecode (str) {return utf8to16 (Base64decode (str));

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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