account for circular references properly, closes #31

Author: nlf

lib/utils.js

@@ -20,7 +20,7 @@ exports.arrayToObject = function (source) {
 };
 
 
-exports.clone = function (source) {
+exports.clone = function (source, refs) {
 
     if (typeof source !== 'object' ||
         source === null) {
@@ -32,14 +32,24 @@ exports.clone = function (source) {
         return source.toString();
     }
 
-    var obj = Array.isArray(source) ? [] : {};
+    refs = refs || [];
+
+    var lookup = refs.indexOf(source);
+    if (lookup !== -1) {
+        return refs[lookup];
+    }
+
+    var copy = Array.isArray(source) ? [] : source;
+
+    refs.push(source);
+
     for (var i in source) {
         if (source.hasOwnProperty(i)) {
-            obj[i] = exports.clone(source[i]);
+            copy[i] = exports.clone(source[i], refs);
         }
     }
 
-    return obj;
+    return copy;
 };
 
 
@@ -108,32 +118,41 @@ exports.decode = function (str) {
 };
 
 
-exports.compact = function (obj) {
+exports.compact = function (obj, refs) {
+
+    if (typeof obj !== 'object' ||
+        obj === null) {
 
-    if (typeof obj !== 'object' || obj === null) {
         return obj;
     }
 
-    var compacted = {};
+    refs = refs || [];
+    var lookup = refs.indexOf(obj);
+    if (lookup !== -1) {
+        return refs[lookup];
+    }
 
-    for (var key in obj) {
-        if (obj.hasOwnProperty(key)) {
-            if (Array.isArray(obj[key])) {
-                compacted[key] = [];
+    refs.push(obj);
 
-                for (var i = 0, l = obj[key].length; i < l; i++) {
-                    if (typeof obj[key][i] !== 'undefined') {
-                        compacted[key].push(obj[key][i]);
-                    }
-                }
-            }
-            else {
-                compacted[key] = exports.compact(obj[key]);
+    if (Array.isArray(obj)) {
+        var compacted = [];
+
+        for (var i = 0, l = obj.length; i < l; ++i) {
+            if (typeof obj[i] !== 'undefined') {
+                compacted.push(obj[i]);
             }
         }
+
+        return compacted;
+    }
+
+    for (var key in obj) {
+        if (obj.hasOwnProperty(key)) {
+            obj[key] = exports.compact(obj[key], refs);
+        }
     }
 
-    return compacted;
+    return obj;
 };
 
 

test/parse.js

@@ -337,4 +337,15 @@ describe('#parse', function () {
         expect(Qs.parse('roomInfoList[0].childrenAges[0]=15&roomInfoList[0].numberOfAdults=2')).to.deep.equal({ roomInfoList: [['15', '2']] });
         done();
     });
+
+    it('does not crash when parsing circular references', function (done) {
+
+        var a = {};
+        a.b = a;
+        expect(function () {
+
+            Qs.parse({ 'foo[bar]': 'baz', 'foo[baz]': a });
+        }).to.not.throw(Error);
+        done();
+    });
 });