fromByteArray(): cache uint8.length value

lib/b64.js

@@ -82,7 +82,8 @@ function encodeChunk (uint8, start, end) {
 
 function fromByteArray (uint8) {
   var i
-  var extraBytes = uint8.length % 3 // if we have 1 byte left, pad 2 bytes
+  var len = uint8.length
+  var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
   var output = ''
   var parts = []
   var temp, length
@@ -90,20 +91,20 @@ function fromByteArray (uint8) {
 
   // go through the array every three bytes, we'll deal with trailing stuff later
 
-  for (i = 0, length = uint8.length - extraBytes; i < length; i += maxChunkLength) {
+  for (i = 0, length = len - extraBytes; i < length; i += maxChunkLength) {
     parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > length ? length : (i + maxChunkLength)))
   }
 
   // pad the end with zeros, but make sure to not forget the extra bytes
   switch (extraBytes) {
     case 1:
-      temp = uint8[uint8.length - 1]
+      temp = uint8[len - 1]
       output += lookup[temp >> 2]
       output += lookup[(temp << 4) & 0x3F]
       output += '=='
       break
     case 2:
-      temp = (uint8[uint8.length - 2] << 8) + (uint8[uint8.length - 1])
+      temp = (uint8[len - 2] << 8) + (uint8[len - 1])
       output += lookup[temp >> 10]
       output += lookup[(temp >> 4) & 0x3F]
       output += lookup[(temp << 2) & 0x3F]