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Javascript base64 encoding and decoding

Source: Internet
Author: User
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<HTML>

<Head>
<Meta http-equiv = "Content-Type" content = "text/html; charset = gb2312">
<Title> base64 </title>
</Head>

<Body>
<Script language = "JavaScript">
VaR keystr = "abcdefghijklmnop" +
"Qrstuvwxyzabcdef" +
"Ghijklmnopqrstuv" +
"Wxyz0123456789 +/" +
"= ";

Function encode64 (input ){
Input = escape (input );
VaR output = "";
VaR chr1, chr2, chr3 = "";
VaR enc1, enc2, enc3, enc4 = "";
VaR I = 0;

Do {
Chr1 = input. charcodeat (I ++ );
Chr2 = input. charcodeat (I ++ );
Chr3 = input. charcodeat (I ++ );

Enc1 = chr1> 2;
Enc2 = (chr1 & 3) <4) | (chr2> 4 );
Enc3 = (chr2 & 15) <2) | (chr3> 6 );
Enc4 = chr3 & 63;

If (isnan (chr2 )){
Enc3 = enc4 = 64;
} Else if (isnan (chr3 )){
Enc4 = 64;
}

Output = output +
Keystr. charat (enc1) +
Keystr. charat (enc2) +
Keystr. charat (enc3) +
Keystr. charat (enc4 );
Chr1 = chr2 = chr3 = "";
Enc1 = enc2 = enc3 = enc4 = "";
} While (I <input. Length );

Return output;
}

Function decode64 (input ){
VaR output = "";
VaR chr1, chr2, chr3 = "";
VaR enc1, enc2, enc3, enc4 = "";
VaR I = 0;

// Remove all characters that are not A-Z, A-Z, 0-9, +,/, OR =
VaR base64test =/[^ A-Za-z0-9/+ // =]/g;
If (base64test.exe C (input )){
Alert ("there were invalid base64 characters in the input text./N" +
"Valid base64 characters are A-Z, A-Z, 0-9, '+', '/', and '='/N" +
"Reverse CT errors in decoding .");
}
Input = input. Replace (/[^ A-Za-z0-9/+ // =]/g ,"");

Do {
Enc1 = keystr. indexof (input. charat (I ++ ));
Enc2 = keystr. indexof (input. charat (I ++ ));
Enc3 = keystr. indexof (input. charat (I ++ ));
Enc4 = keystr. indexof (input. charat (I ++ ));

Chr1 = (enc1 <2) | (enc2> 4 );
Chr2 = (enc2 & 15) <4) | (enc3> 2 );
Chr3 = (enc3 & 3) <6) | enc4;

Output = output + String. fromcharcode (chr1 );

If (enc3! = 64 ){
Output = output + String. fromcharcode (chr2 );
}
If (enc4! = 64 ){
Output = output + String. fromcharcode (chr3 );
}

Chr1 = chr2 = chr3 = "";
Enc1 = enc2 = enc3 = enc4 = "";

} While (I <input. Length );

Return Unescape (output );
}

</SCRIPT>

<Form method = "Post" Action = "-- WEBBOT-SELF --">
<Table border = "1" width = "100%" style = "border-collapse: collapse">
<Tr>
<TD> <textarea rows = "20" name = "S1" Cols = "57"> </textarea> </TD>
<TD> <input type = "button" value = "base64decode -- & gt;" name = "B1" onclick = "s2.value = decode64 (s1.value);"> <br>
<Input type = "button" value = "& lt; -- base64encode" name = "B2" onclick = "s1.value = encode64 (s2.value)"> </TD>
<TD> <textarea rows = "20" name = "S2" Cols = "56"> </textarea> </TD>
</Tr>
<Tr>
<TD> </TD>
<TD> </TD>
<TD> </TD>
</Tr>
</Table>

</Form>
</Body>

</Html>

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.

Related Keywords:
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