Add arrayFormat option

This commit adds the arrayFormat option to qs.stringify. Valid
values are "indices" (the default), "repeat", or "brackets".

Backwards compat is preserved with the indices option as well.

lib/stringify.js

@@ -7,11 +7,21 @@ var Utils = require('./utils');
 
 var internals = {
     delimiter: '&',
-    indices: true
+    arrayPrefixGenerators: {
+        brackets: function (prefix, key) {
+            return prefix + '[]';
+        },
+        indices: function (prefix, key) {
+            return prefix + '[' + key + ']';
+        },
+        repeat: function (prefix, key) {
+            return prefix;
+        }
+    }
 };
 
 
-internals.stringify = function (obj, prefix, options) {
+internals.stringify = function (obj, prefix, generateArrayPrefix) {
 
     if (Utils.isBuffer(obj)) {
         obj = obj.toString();
@@ -39,13 +49,11 @@ internals.stringify = function (obj, prefix, options) {
     var objKeys = Object.keys(obj);
     for (var i = 0, il = objKeys.length; i < il; ++i) {
         var key = objKeys[i];
-        if (!options.indices &&
-            Array.isArray(obj)) {
-
-            values = values.concat(internals.stringify(obj[key], prefix, options));
+        if (Array.isArray(obj)) {
+            values = values.concat(internals.stringify(obj[key], generateArrayPrefix(prefix, key), generateArrayPrefix));
         }
         else {
-            values = values.concat(internals.stringify(obj[key], prefix + '[' + key + ']', options));
+            values = values.concat(internals.stringify(obj[key], prefix + '[' + key + ']', generateArrayPrefix));
         }
     }
 
@@ -57,7 +65,6 @@ module.exports = function (obj, options) {
 
     options = options || {};
     var delimiter = typeof options.delimiter === 'undefined' ? internals.delimiter : options.delimiter;
-    options.indices = typeof options.indices === 'boolean' ? options.indices : internals.indices;
 
     var keys = [];
 
@@ -67,10 +74,23 @@ module.exports = function (obj, options) {
         return '';
     }
 
+    var arrayFormat;
+    if (options.arrayFormat in internals.arrayPrefixGenerators) {
+        arrayFormat = options.arrayFormat;
+    }
+    else if ('indices' in options) {
+        arrayFormat = options.indices ? 'indices' : 'repeat';
+    }
+    else {
+        arrayFormat = 'indices';
+    }
+
+    var generateArrayPrefix = internals.arrayPrefixGenerators[arrayFormat];
+
     var objKeys = Object.keys(obj);
     for (var i = 0, il = objKeys.length; i < il; ++i) {
         var key = objKeys[i];
-        keys = keys.concat(internals.stringify(obj[key], key, options));
+        keys = keys.concat(internals.stringify(obj[key], key, generateArrayPrefix));
     }
 
     return keys.join(delimiter);

test/stringify.js

@@ -67,6 +67,36 @@ describe('stringify()', function () {
         done();
     });
 
+    it('uses indices notation for arrays when indices=true', function (done) {
+
+        expect(Qs.stringify({ a: ['b', 'c'] }, { indices: true })).to.equal('a%5B0%5D=b&a%5B1%5D=c');
+        done();
+    });
+
+    it('uses indices notation for arrays when no arrayFormat is specified', function (done) {
+
+        expect(Qs.stringify({ a: ['b', 'c'] })).to.equal('a%5B0%5D=b&a%5B1%5D=c');
+        done();
+    });
+
+    it('uses indices notation for arrays when no arrayFormat=indices', function (done) {
+
+        expect(Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'indices' })).to.equal('a%5B0%5D=b&a%5B1%5D=c');
+        done();
+    });
+
+    it('uses repeat notation for arrays when no arrayFormat=repeat', function (done) {
+
+        expect(Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'repeat' })).to.equal('a=b&a=c');
+        done();
+    });
+
+    it('uses brackets notation for arrays when no arrayFormat=brackets', function (done) {
+
+        expect(Qs.stringify({ a: ['b', 'c'] }, { arrayFormat: 'brackets' })).to.equal('a%5B%5D=b&a%5B%5D=c');
+        done();
+    });
+
     it('stringifies a complicated object', function (done) {
 
         expect(Qs.stringify({ a: { b: 'c', d: 'e' } })).to.equal('a%5Bb%5D=c&a%5Bd%5D=e');