Cleanup and Test: base64.js

This is the first commit in a series of commits
which improve the readability of some of the code
and add tests.

File: base64.js
Tests Added: True
Changes:
- Improved indentation
- Fixed JSHint errors
- Moved loop variables to be declared in the loop for better readability
  (N.B. Javascript does not have block scoping, so the variables are
  still technically available outside the loop -- it just makes the code
  clearer to place them inside the loop, since they are only used there)

include/base64.js

@@ -4,38 +4,36 @@
 
 // From: http://hg.mozilla.org/mozilla-central/raw-file/ec10630b1a54/js/src/devtools/jint/sunspider/string-base64.js
 
-/*jslint white: false, bitwise: false, plusplus: false */
+/*jslint white: false */
 /*global console */
 
 var Base64 = {
+    /* Convert data (an array of integers) to a Base64 string. */
+    toBase64Table : 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='.split(''),
+    base64Pad     : '=',
 
-/* Convert data (an array of integers) to a Base64 string. */
-toBase64Table : 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='.split(''),
-base64Pad     : '=',
-
-encode: function (data) {
+    encode: function (data) {
         "use strict";
         var result = '';
         var toBase64Table = Base64.toBase64Table;
-    var length = data.length
-    var lengthpad = (length%3);
-    var i = 0, j = 0;
+        var length = data.length;
+        var lengthpad = (length % 3);
         // Convert every three bytes to 4 ascii characters.
-  /* BEGIN LOOP */
-    for (i = 0; i < (length - 2); i += 3) {
+
+        for (var i = 0; i < (length - 2); i += 3) {
             result += toBase64Table[data[i] >> 2];
-        result += toBase64Table[((data[i] & 0x03) << 4) + (data[i+1] >> 4)];
-        result += toBase64Table[((data[i+1] & 0x0f) << 2) + (data[i+2] >> 6)];
-        result += toBase64Table[data[i+2] & 0x3f];
+            result += toBase64Table[((data[i] & 0x03) << 4) + (data[i + 1] >> 4)];
+            result += toBase64Table[((data[i + 1] & 0x0f) << 2) + (data[i + 2] >> 6)];
+            result += toBase64Table[data[i + 2] & 0x3f];
         }
-  /* END LOOP */
 
         // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
+        var j = 0;
         if (lengthpad === 2) {
             j = length - lengthpad;
             result += toBase64Table[data[j] >> 2];
-        result += toBase64Table[((data[j] & 0x03) << 4) + (data[j+1] >> 4)];
-        result += toBase64Table[(data[j+1] & 0x0f) << 2];
+            result += toBase64Table[((data[j] & 0x03) << 4) + (data[j + 1] >> 4)];
+            result += toBase64Table[(data[j + 1] & 0x0f) << 2];
             result += toBase64Table[64];
         } else if (lengthpad === 1) {
             j = length - lengthpad;
@@ -46,10 +44,11 @@ encode: function (data) {
         }
 
         return result;
-},
+    },
 
-/* Convert Base64 data to a string */
-toBinaryTable : [
+    /* Convert Base64 data to a string */
+    /* jshint -W013 */
+    toBinaryTable : [
         -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,
@@ -58,14 +57,15 @@ toBinaryTable : [
         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
-],
+    ],
+    /* jshint +W013 */
 
-decode: function (data, offset) {
+    decode: function (data, offset) {
         "use strict";
         offset = typeof(offset) !== 'undefined' ? offset : 0;
         var toBinaryTable = Base64.toBinaryTable;
         var base64Pad = Base64.base64Pad;
-    var result, result_length, idx, i, c, padding;
+        var result, result_length;
         var leftbits = 0; // number of bits decoded, but yet to be appended
         var leftdata = 0; // bits decoded, but yet to be appended
         var data_length = data.indexOf('=') - offset;
@@ -73,14 +73,13 @@ decode: function (data, offset) {
         if (data_length < 0) { data_length = data.length - offset; }
 
         /* Every four characters is 3 resulting numbers */
-    result_length = (data_length >> 2) * 3 + Math.floor((data_length%4)/1.5);
+        result_length = (data_length >> 2) * 3 + Math.floor((data_length % 4) / 1.5);
         result = new Array(result_length);
 
         // Convert one by one.
-  /* BEGIN LOOP */
-    for (idx = 0, i = offset; i < data.length; i++) {
-        c = toBinaryTable[data.charCodeAt(i) & 0x7f];
-        padding = (data.charAt(i) === base64Pad);
+        for (var idx = 0, i = offset; i < data.length; i++) {
+            var c = toBinaryTable[data.charCodeAt(i) & 0x7f];
+            var padding = (data.charAt(i) === base64Pad);
             // Skip illegal characters and whitespace
             if (c === -1) {
                 console.error("Illegal character code " + data.charCodeAt(i) + " at position " + i);
@@ -101,15 +100,14 @@ decode: function (data, offset) {
                 leftdata &= (1 << leftbits) - 1;
             }
         }
-  /* END LOOP */
 
         // If there are any bits left, the base64 string was corrupted
         if (leftbits) {
-        throw {name: 'Base64-Error', 
-               message: 'Corrupted base64 string'};
+            err = new Error('Corrupted base64 string');
+            err.name = 'Base64-Error';
+            throw err;
         }
 
         return result;
-}
-
+    }
 }; /* End of Base64 namespace */

tests/test.base64.js

+// requires local modules: base64
+var assert = chai.assert;
+var expect = chai.expect;
+
+describe('Base64 Tools', function() {
+    "use strict";
+
+    var BIN_ARR = new Array(256);
+    for (var i = 0; i < 256; i++) {
+        BIN_ARR[i] = i;
+    }
+    
+    var B64_STR = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6/wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w==";
+
+
+    describe('encode', function() {
+        it('should encode a binary string into Base64', function() {
+            var encoded = Base64.encode(BIN_ARR);
+            expect(encoded).to.equal(B64_STR);
+        });
+    });
+
+    describe('decode', function() {
+        it('should decode a Base64 string into a normal string', function() {
+            var decoded = Base64.decode(B64_STR);
+            expect(decoded).to.deep.equal(BIN_ARR);
+        });
+
+        it('should throw an error if we have extra characters at the end of the string', function() {
+            expect(function () { Base64.decode(B64_STR+'abcdef'); }).to.throw(Error);
+        });
+    });
+});