javascript에서 Base64 인코딩/디코딩
var enc64List, dec64List;
function initBase64() {
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;
}
}
function base64Encode(str) {
var c, d, e, end = 0;
var u, v, w, x;
var ptr = -1;
var input = str.split("");
var output = "";
while(end == 0) {
c = (typeof input[++ptr] != "undefined") ? input[ptr].charCodeAt(0) :
((end = 1) ? 0 : 0);
d = (typeof input[++ptr] != "undefined") ? input[ptr].charCodeAt(0) :
((end += 1) ? 0 : 0);
e = (typeof input[++ptr] != "undefined") ? input[ptr].charCodeAt(0) :
((end += 1) ? 0 : 0);
u = enc64List[c >> 2];
v = enc64List[(0x00000003 & c) << 4 | d >> 4];
w = enc64List[(0x0000000F & d) << 2 | e >> 6];
x = enc64List[e & 0x0000003F];
if (end >= 1) {x = "=";}
if (end == 2) {w = "=";}
if (end < 3) {output += u + v + w + x;}
}
var formattedOutput = "";
var lineLength = 76;
while (output.length > lineLength) {
formattedOutput += output.substring(0, lineLength) + "\n";
output = output.substring(lineLength);
}
formattedOutput += output;
return formattedOutput;
}
function base64Decode(str) {
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;
}
initBase64();