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

@@ -4,112 +4,110 @@
 
 // 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     : '=',
+
+    encode: function (data) {
+        "use strict";
+        var result = '';
+        var toBase64Table = Base64.toBase64Table;
+        var length = data.length;
+        var lengthpad = (length % 3);
+        // Convert every three bytes to 4 ascii characters.
+
+        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];
+        }
 
-/* Convert data (an array of integers) to a Base64 string. */
-toBase64Table : 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='.split(''),
-base64Pad     : '=',
-
-encode: function (data) {
-    "use strict";
-    var result = '';
-    var toBase64Table = Base64.toBase64Table;
-    var length = data.length
-    var lengthpad = (length%3);
-    var i = 0, j = 0;
-    // Convert every three bytes to 4 ascii characters.
-  /* BEGIN LOOP */
-    for (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];
-    }
-  /* END LOOP */
-
-    // Convert the remaining 1 or 2 bytes, pad out to 4 characters.
-    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[64];
-    } else if (lengthpad === 1) {
-        j = length - lengthpad;
-        result += toBase64Table[data[j] >> 2];
-        result += toBase64Table[(data[j] & 0x03) << 4];
-        result += toBase64Table[64];
-        result += toBase64Table[64];
-    }
-
-    return result;
-},
-
-/* Convert Base64 data to a string */
-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,
-    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-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
-],
-
-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 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;
-
-    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 = 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);
-        // Skip illegal characters and whitespace
-        if (c === -1) {
-            console.error("Illegal character code " + data.charCodeAt(i) + " at position " + i);
-            continue;
+        // 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[64];
+        } else if (lengthpad === 1) {
+            j = length - lengthpad;
+            result += toBase64Table[data[j] >> 2];
+            result += toBase64Table[(data[j] & 0x03) << 4];
+            result += toBase64Table[64];
+            result += toBase64Table[64];
         }
-        
-        // Collect data into leftdata, update bitcount
-        leftdata = (leftdata << 6) | c;
-        leftbits += 6;
 
-        // If we have 8 or more bits, append 8 bits to the result
-        if (leftbits >= 8) {
-            leftbits -= 8;
-            // Append if not padding.
-            if (!padding) {
-                result[idx++] = (leftdata >> leftbits) & 0xff;
+        return result;
+    },
+
+    /* 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,
+        52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-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
+    ],
+    /* jshint +W013 */
+
+    decode: function (data, offset) {
+        "use strict";
+        offset = typeof(offset) !== 'undefined' ? offset : 0;
+        var toBinaryTable = Base64.toBinaryTable;
+        var base64Pad = Base64.base64Pad;
+        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;
+
+        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 = new Array(result_length);
+
+        // Convert one by one.
+        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);
+                continue;
+            }
+          
+            // Collect data into leftdata, update bitcount
+            leftdata = (leftdata << 6) | c;
+            leftbits += 6;
+
+            // If we have 8 or more bits, append 8 bits to the result
+            if (leftbits >= 8) {
+                leftbits -= 8;
+                // Append if not padding.
+                if (!padding) {
+                    result[idx++] = (leftdata >> leftbits) & 0xff;
+                }
+                leftdata &= (1 << leftbits) - 1;
             }
-            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'};
-    }
-
-    return result;
-}
+        // If there are any bits left, the base64 string was corrupted
+        if (leftbits) {
+            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);
+        });
+    });
+});