javascript base64编码解码

最新推荐文章于 2022-08-06 16:57:32 发布

iteye_11687

最新推荐文章于 2022-08-06 16:57:32 发布

阅读量89

点赞数

文章标签： javascript ViewUI

本文介绍了一个简单的Base64编码与解码的JavaScript实现。通过提供的代码示例，读者可以了解如何将普通文本转换为Base64格式，以及如何从Base64格式还原回原始文本。该实现包括对非法字符的检查，并提供了友好的错误提示。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

<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.exec(input)) {
alert("There were invalid base64 characters in the input text./n" +
"Valid base64 characters are A-Z, a-z, 0-9, '+', '/', and '='/n" +
"Expect 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-->" name="B1" onclick="S2.value=decode64(S1.value);"><br>
<input type="button" value="<--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>