Add square brackets to prefixes with arrayFormat: comma

README.md

@@ -275,10 +275,15 @@ assert.deepEqual(arraysOfObjects, { a: [{ b: 'c' }] });
 
 Some people use comma to join array, **qs** can parse it:
 ```javascript
+var arraysOfObjects = qs.parse('a[]=b,c', { comma: true })
+assert.deepEqual(arraysOfObjects, { a: ['b', 'c'] })
+```
+or
+```javascript
 var arraysOfObjects = qs.parse('a=b,c', { comma: true })
 assert.deepEqual(arraysOfObjects, { a: ['b', 'c'] })
 ```
-(_this cannot convert nested objects, such as `a={b:1},{c:d}`_)
+(_this cannot convert nested objects, such as `a[]={b:1},{c:d}`_)
 
 ### Stringifying
 
@@ -356,7 +361,7 @@ qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'brackets' })
 qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'repeat' })
 // 'a=b&a=c'
 qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'comma' })
-// 'a=b,c'
+// 'a[]=b,c'
 ```
 
 When objects are stringified, by default they use bracket notation:

lib/stringify.js

@@ -8,7 +8,9 @@ var arrayPrefixGenerators = {
     brackets: function brackets(prefix) { // eslint-disable-line func-name-matching
         return prefix + '[]';
     },
-    comma: 'comma',
+    comma: function comma(prefix) { // eslint-disable-line func-name-matching
+        return prefix + '[]';
+    },
     indices: function indices(prefix, key) { // eslint-disable-line func-name-matching
         return prefix + '[' + key + ']';
     },
@@ -57,6 +59,7 @@ var isNonNullishPrimitive = function isNonNullishPrimitive(v) { // eslint-disabl
 var stringify = function stringify( // eslint-disable-line func-name-matching
     object,
     prefix,
+    arrayFormat,
     generateArrayPrefix,
     strictNullHandling,
     skipNulls,
@@ -74,8 +77,10 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
         obj = filter(prefix, obj);
     } else if (obj instanceof Date) {
         obj = serializeDate(obj);
-    } else if (generateArrayPrefix === 'comma' && isArray(obj)) {
+    } else if (arrayFormat === 'comma' && isArray(obj)) {
         obj = obj.join(',');
+        // eslint-disable-next-line no-param-reassign
+        prefix = generateArrayPrefix(prefix);
     }
 
     if (obj === null) {
@@ -119,6 +124,7 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
             pushToArray(values, stringify(
                 obj[key],
                 typeof generateArrayPrefix === 'function' ? generateArrayPrefix(prefix, key) : prefix,
+                arrayFormat,
                 generateArrayPrefix,
                 strictNullHandling,
                 skipNulls,
@@ -135,6 +141,7 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
             pushToArray(values, stringify(
                 obj[key],
                 prefix + (allowDots ? '.' + key : '[' + key + ']'),
+                arrayFormat,
                 generateArrayPrefix,
                 strictNullHandling,
                 skipNulls,
@@ -248,6 +255,7 @@ module.exports = function (object, opts) {
         pushToArray(keys, stringify(
             obj[key],
             key,
+            arrayFormat,
             generateArrayPrefix,
             options.strictNullHandling,
             options.skipNulls,

test/parse.js

@@ -361,6 +361,7 @@ test('parse()', function (t) {
 
     t.test('parses string with comma as array divider', function (st) {
         st.deepEqual(qs.parse('foo=bar,tee', { comma: true }), { foo: ['bar', 'tee'] });
+        st.deepEqual(qs.parse('foo[]=bar,tee', { comma: true }), { foo: ['bar', 'tee'] });
         st.deepEqual(qs.parse('foo[bar]=coffee,tee', { comma: true }), { foo: { bar: ['coffee', 'tee'] } });
         st.deepEqual(qs.parse('foo=', { comma: true }), { foo: '' });
         st.deepEqual(qs.parse('foo', { comma: true }), { foo: '' });

test/stringify.js

@@ -105,7 +105,7 @@ test('stringify()', function (t) {
         );
         st.equal(
             qs.stringify({ a: ['b', 'c', 'd'] }, { arrayFormat: 'comma' }),
-            'a=b%2Cc%2Cd',
+            'a%5B%5D=b%2Cc%2Cd',
             'comma => comma'
         );
         st.equal(
@@ -134,7 +134,7 @@ test('stringify()', function (t) {
     t.test('stringifies a nested array value', function (st) {
         st.equal(qs.stringify({ a: { b: ['c', 'd'] } }, { arrayFormat: 'indices' }), 'a%5Bb%5D%5B0%5D=c&a%5Bb%5D%5B1%5D=d');
         st.equal(qs.stringify({ a: { b: ['c', 'd'] } }, { arrayFormat: 'brackets' }), 'a%5Bb%5D%5B%5D=c&a%5Bb%5D%5B%5D=d');
-        st.equal(qs.stringify({ a: { b: ['c', 'd'] } }, { arrayFormat: 'comma' }), 'a%5Bb%5D=c%2Cd'); // a[b]=c,d
+        st.equal(qs.stringify({ a: { b: ['c', 'd'] } }, { arrayFormat: 'comma' }), 'a%5Bb%5D%5B%5D=c%2Cd'); // a[b][]=c,d
         st.equal(qs.stringify({ a: { b: ['c', 'd'] } }), 'a%5Bb%5D%5B0%5D=c&a%5Bb%5D%5B1%5D=d');
         st.end();
     });
@@ -161,7 +161,7 @@ test('stringify()', function (t) {
                 { a: { b: ['c', 'd'] } },
                 { allowDots: true, encode: false, arrayFormat: 'comma' }
             ),
-            'a.b=c,d',
+            'a.b[]=c,d',
             'comma: stringifies with dots + comma'
         );
         st.equal(
@@ -719,5 +719,15 @@ test('stringify()', function (t) {
         st.end();
     });
 
+    t.test('stringifies a comma array value with single element', function (st) {
+        st.equal(
+            qs.stringify({ a: ['b'] }, { arrayFormat: 'comma' }),
+            'a%5B%5D=b',
+            'comma => comma'
+        );
+
+        st.end();
+    });
+
     t.end();
 });