Base64Encoding 演示代码[JavaScript]

很简单的代码,用来做算法示范再好不过了,来自 一只猿

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function Base64Encoding(input)
{
var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
var output = "";
var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
var i = 0;
input = utf8_encode(input);
while (i < input.length)
{
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);
}
return output;
}