problems(js): add “2628. JSON Deep Equal”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/js/json-deep-equal.js

@@ -0,0 +1,38 @@
+/**
+ * @param {any} o1
+ * @param {any} o2
+ * @return {boolean}
+ */
+var areDeeplyEqual = function(o1, o2) {
+    // passes strict equality
+    if (o1 === o2) {
+        return true;
+    }
+
+    // one is ‹null›
+    if (o1 === null || o2 === null) {
+        return false;
+    }
+
+    // different string representations
+    if (String(o1) != String(o2)) {
+        return false;
+    }
+
+    // if it's not an object we can decide with strict equality
+    if (typeof o1 !== 'object') {
+        return o1 === o2;
+    }
+
+    if (Array.isArray(o1)) {
+        return (
+            o1.length === o2.length
+            && Array.from(o1.keys()).every(i => areDeeplyEqual(o1[i], o2[i]))
+        );
+    }
+
+    return (
+        Object.keys(o1).length === Object.keys(o2).length
+        && Object.keys(o1).every(key => areDeeplyEqual(o1[key], o2[key]))
+    );
+};