Support enumerable symbol properties in deepEqual()

Author: kanongil

lib/deep-equal.js

@@ -116,7 +116,7 @@ internals.isSetSimpleEqual = function (obj, ref) {
 internals.isDeepEqualObj = function (instanceType, obj, ref, options, seen) {
 
     const { isDeepEqual, valueOf, hasOwnEnumerableProperty } = internals;
-    const { keys } = Object;
+    const { keys, getOwnPropertySymbols } = Object;
 
     if (instanceType === internals.arrayType) {
         if (options.part) {
@@ -226,6 +226,36 @@ internals.isDeepEqualObj = function (instanceType, obj, ref, options, seen) {
         }
     }
 
+    // Check symbols
+
+    const objSymbols = getOwnPropertySymbols(obj);
+    const refSymbols = new Set(getOwnPropertySymbols(ref));
+
+    for (let i = 0; i < objSymbols.length; ++i) {
+        const key = objSymbols[i];
+
+        if (hasOwnEnumerableProperty(obj, key)) {
+            if (!hasOwnEnumerableProperty(ref, key)) {
+                return false;
+            }
+
+            if (!isDeepEqual(obj[key], ref[key], options, seen)) {
+                return false;
+            }
+        }
+        else if (hasOwnEnumerableProperty(ref, key)) {
+            return false;
+        }
+
+        refSymbols.delete(key);
+    }
+
+    for (const key of refSymbols) {
+        if (hasOwnEnumerableProperty(ref, key)) {
+            return false;
+        }
+    }
+
     return true;
 };
 

test/index.js

@@ -1083,6 +1083,27 @@ describe('deepEqual()', () => {
         compare();
     });
 
+    it('compares symbol object properties', () => {
+
+        const sym = Symbol();
+
+        const ne = {};
+        Object.defineProperty(ne, sym, { value: true });
+
+        expect(Hoek.deepEqual({ [sym]: { c: true } }, { [sym]: { c: true } })).to.be.true();
+        expect(Hoek.deepEqual({ [sym]: { c: true } }, { [sym]: { c: false } })).to.be.false();
+        expect(Hoek.deepEqual({ [sym]: { c: true } }, { [sym]: true })).to.be.false();
+        expect(Hoek.deepEqual({ [sym]: undefined }, { [sym]: undefined })).to.be.true();
+        expect(Hoek.deepEqual({ [sym]: undefined }, {})).to.be.false();
+        expect(Hoek.deepEqual({}, { [sym]: undefined })).to.be.false();
+
+        expect(Hoek.deepEqual({}, ne)).to.be.true();
+        expect(Hoek.deepEqual(ne, {})).to.be.true();
+        expect(Hoek.deepEqual({ [sym]: true }, ne)).to.be.false();
+        expect(Hoek.deepEqual(ne, { [sym]: true })).to.be.false();
+        expect(Hoek.deepEqual(ne, { [Symbol()]: undefined })).to.be.false();
+    });
+
     it('compares dates', () => {
 
         expect(Hoek.deepEqual(new Date(2015, 1, 1), new Date('2015/02/01'))).to.be.true();