<br />
function
na(a) {<br />
if
(!a)
return
""
;<br />
var
a = a.toString(),<br /> c, b, f, i, e, h = [-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];<br /> i = a.length;<br /> f = 0;<br />
for
(e =
""
; f < i;) {<br />
do
c = h[a.charCodeAt(f++) & 255];
while
(f < i && -1 == c);<br />
if
(-1 == c)
break
;<br />
do
b = h[a.charCodeAt(f++) & 255];
while
(f < i && -1 == b);<br />
if
(-1 == b)
break
;<br /> e += String.fromCharCode(c << 2 | (b & 48) >> 4);<br />
do
{<br /> c = a.charCodeAt(f++) & 255;<br />
if
(61 == c)
return
e;<br /> c = h[c]<br /> }
while
(f < i && -1 == c);<br />
if
(-1 == c)
break
;<br /> e += String.fromCharCode((b & 15) << 4 | (c & 60) >> 2);<br />
do
{<br /> b = a.charCodeAt(f++) & 255;<br />
if
(61 == b)
return
e;<br /> b = h[b]<br /> }
while
(f < i && -1 == b);<br />
if
(-1 == b)
break
;<br /> e += String.fromCharCode((c & 3) << 6 | b)<br /> }<br />
return
e<br />}<br />