feat: add extra capabitlity to extends on fly generation

index.js

@@ -29,7 +29,10 @@ const {
  */
 
 /**
+ * Function iterator, [see](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator/next)
+ * [examples](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Iterators_and_Generators#Advanced_generators)
  * @callback TraverseIterator
+ * @param extra a object or array to extends the current iteration
  * @returns {TraverseIteratorResult}
  */
 
@@ -223,11 +226,15 @@ const traverseJson = (obj, opts) => {
 
   dive(obj);
 
-  const next = () => {
+  let prefix, value;
+  const next = (extra) => {
+    if (extra !== undefined) {
+      dive(extra, prefix);
+    }
     if (cursor < overall.length) {
-      let entry = overall[cursor];
+      let entry = overall[cursor] || [];
+      [prefix, value] = entry;
       if (recursive) {
-        const [prefix, value] = entry || [];
         if (isTraversable(value)) {
           dive(value, prefix);
           if (!nested) {
@@ -246,6 +253,7 @@ const traverseJson = (obj, opts) => {
 
       return { value: entry, done: false };
     }
+
     return { done: true };
   };
 

test.js

@@ -247,6 +247,60 @@ test('should iterate recursively through the same key', (t) => {
   iterateEqual(t, ientries, expected, true);
 });
 
+test('should extends on fly the iterator', (t) => {
+
+  const recursiveObject = {
+    nested: 'foo',
+  };
+
+  const expected = [
+    [ '/nested', 'foo' ],
+    [ '/nested/nested', 'foo' ],
+    [ '/nested/nested/nested', 'foo' ],
+    [ '/nested/nested/nested/nested', 'foo' ],
+    [ '/nested/nested/nested/nested/nested', 'foo' ],
+  ];
+
+  const iteratee = traverseObject(recursiveObject);
+
+  for (let i = 0; i < 5; i ++) {
+    const { value, done } = iteratee(recursiveObject);
+    t.deepEqual(value, expected[i]);
+    t.false(done);
+  }
+
+  const { done } = iteratee();
+  t.true(done);
+});
+
+test('should extends on fly the iterator with nested paths', (t) => {
+
+  const recursiveObject = {
+    nested: {
+      foo: 'bar',
+    },
+  };
+
+  const expected = [
+    [ '/nested', { foo: 'bar' } ],
+    [ '/nested/nested', { foo: 'bar' } ],
+    [ '/nested/nested/nested', { foo: 'bar' } ],
+    [ '/nested/nested/nested/nested', { foo: 'bar' } ],
+    [ '/nested/nested/nested/nested/nested', { foo: 'bar' } ],
+  ];
+
+  const iteratee = traverseObject(recursiveObject, { test: '@nested' });
+
+  for (let i = 0; i < 5; i ++) {
+    const { value, done } = iteratee(recursiveObject);
+    t.deepEqual(value, expected[i]);
+    t.false(done);
+  }
+
+  const { done } = iteratee();
+  t.true(done);
+});
+
 test('should works as iterable', (t) => {
 
   const { createIterator } = traverseObject;