概述
为什么80%的码农都做不了架构师？>>> 
function base64_encode(str)
{
var str = toUTF8(str);
var base64EncodeChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split('');
var out, i, j, len, r, l, c;
i = j = 0;
len = str.length;
r = len % 3;
len = len - r;
l = (len / 3) << 2;
if (r > 0) {
l += 4;
}
out = new Array(l);
while (i < len) {
c = str.charCodeAt(i++) << 16 |
str.charCodeAt(i++) << 8 |
str.charCodeAt(i++);
out[j++] = base64EncodeChars[c >> 18]
+ base64EncodeChars[c >> 12 & 0x3f]
+ base64EncodeChars[c >> 6 & 0x3f]
+ base64EncodeChars[c & 0x3f] ;
}
if (r == 1) {
c = str.charCodeAt(i++);
out[j++] = base64EncodeChars[c >> 2]
+ base64EncodeChars[(c & 0x03) << 4]
+ "==";
}
else if (r == 2) {
c = str.charCodeAt(i++) << 8 |
str.charCodeAt(i++);
out[j++] = base64EncodeChars[c >> 10]
+ base64EncodeChars[c >> 4 & 0x3f]
+ base64EncodeChars[(c & 0x0f) << 2]
+ "=";
}
return out.join('');
}
function base64_decode(str)
{
var base64DecodeChars = [
-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, -1, 62, -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,
-1, 26, 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 c1, c2, c3, c4;
var i, j, len, r, l, out;
len = str.length;
if (len % 4 != 0) {
return '';
}
if (/[^ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=]/.test(str)) {
return '';
}
if (str.charAt(len - 2) == '=') {
r = 1;
}
else if (str.charAt(len - 1) == '=') {
r = 2;
}
else {
r = 0;
}
l = len;
if (r > 0) {
l -= 4;
}
l = (l >> 2) * 3 + r;
out = new Array(l);
i = j = 0;
while (i < len) {
// c1
c1 = base64DecodeChars[str.charCodeAt(i++)];
if (c1 == -1) break;
// c2
c2 = base64DecodeChars[str.charCodeAt(i++)];
if (c2 == -1) break;
out[j++] = String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
// c3
c3 = base64DecodeChars[str.charCodeAt(i++)];
if (c3 == -1) break;
out[j++] = String.fromCharCode(((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2));
// c4
c4 = base64DecodeChars[str.charCodeAt(i++)];
if (c4 == -1) break;
out[j++] = String.fromCharCode(((c3 & 0x03) << 6) | c4);
}
return toUTF16(out.join(''));
}
function toUTF8(str)
{
if (str.match(/^[x00-x7f]*$/) != null) {
return str.toString();
}
var out, i, j, len, c, c2;
out = [];
len = str.length;
for (i = 0, j = 0; i < len; i++, j++) {
c = str.charCodeAt(i);
if (c <= 0x7f) {
out[j] = str.charAt(i);
}
else if (c <= 0x7ff) {
out[j] = String.fromCharCode(0xc0 | (c >>> 6),
0x80 | (c & 0x3f));
}
else if (c < 0xd800 || c > 0xdfff) {
out[j] = String.fromCharCode(0xe0 | (c >>> 12),
0x80 | ((c >>> 6) & 0x3f),
0x80 | (c & 0x3f));
}
else {
if (++i < len) {
c2 = str.charCodeAt(i);
if (c <= 0xdbff && 0xdc00 <= c2 && c2 <= 0xdfff) {
c = ((c & 0x03ff) << 10 | (c2 & 0x03ff)) + 0x010000;
if (0x010000 <= c && c <= 0x10ffff) {
out[j] = String.fromCharCode(0xf0 | ((c >>> 18) & 0x3f),
0x80 | ((c >>> 12) & 0x3f),
0x80 | ((c >>> 6) & 0x3f),
0x80 | (c & 0x3f));
}
else {
out[j] = '?';
}
}
else {
i--;
out[j] = '?';
}
}
else {
i--;
out[j] = '?';
}
}
}
return out.join('');
}
function toUTF16(str)
{
if ((str.match(/^[x00-x7f]*$/) != null) ||
(str.match(/^[x00-xff]*$/) == null)) {
return str.toString();
}
var out, i, j, len, c, c2, c3, c4, s;
out = [];
len = str.length;
i = j = 0;
while (i < len) {
c = str.charCodeAt(i++);
switch (c >> 4) {
case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
// 0xxx xxxx
out[j++] = str.charAt(i - 1);
break;
case 12: case 13:
// 110x xxxx 10xx xxxx
c2 = str.charCodeAt(i++);
out[j++] = String.fromCharCode(((c & 0x1f) << 6) |
(c2 & 0x3f));
break;
case 14:
// 1110 xxxx 10xx xxxx 10xx xxxx
c2 = str.charCodeAt(i++);
c3 = str.charCodeAt(i++);
out[j++] = String.fromCharCode(((c & 0x0f) << 12) |
((c2 & 0x3f) << 6) |
(c3 & 0x3f));
break;
case 15:
switch (c & 0xf) {
case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
// 1111 0xxx 10xx xxxx 10xx xxxx 10xx xxxx
c2 = str.charCodeAt(i++);
c3 = str.charCodeAt(i++);
c4 = str.charCodeAt(i++);
s = ((c & 0x07) << 18) |
((c2 & 0x3f) << 12) |
((c3 & 0x3f) << 6) |
(c4 & 0x3f) - 0x10000;
if (0 <= s && s <= 0xfffff) {
out[j++] = String.fromCharCode(((s >>> 10) & 0x03ff) | 0xd800,
(s & 0x03ff) | 0xdc00);
}
else {
out[j++] = '?';
}
break;
case 8: case 9: case 10: case 11:
// 1111 10xx 10xx xxxx 10xx xxxx 10xx xxxx 10xx xxxx
i+=4;
out[j++] = '?';
break;
case 12: case 13:
// 1111 110x 10xx xxxx 10xx xxxx 10xx xxxx 10xx xxxx 10xx xxxx
i+=5;
out[j++] = '?';
break;
}
}
}
return out.join('');
}转载于:https://my.oschina.net/Jacker/blog/87170
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