Fix an issue with falsy values in deepGet

snippets/deepGet.md

@@ -10,7 +10,42 @@ Use `Array.prototype.reduce()` to get value from nested JSON object one by one.
 If the key exists in object, return target value, otherwise, return `null`.
 
 ```js
-const deepGet = (obj, keys) => keys.reduce((xs, x) => (xs && xs[x] ? xs[x] : null), obj);
+---
+title: deepGet
+tags: object,intermediate
+---
+
+Returns the target value in a nested JSON object, based on the `keys` array.
+
+Compare the keys you want in the nested JSON object as an `Array`.
+Use `Array.prototype.reduce()` to get value from nested JSON object one by one. 
+If the key exists in object, return target value, otherwise, return `null`.
+
+```js
+const deepGet = (obj, keys) =>
+  keys.reduce(
+    (xs, x) => (xs && xs[x] !== null && xs[x] !== undefined ? xs[x] : null),
+    obj
+  );
+```
+
+```js
+let index = 2;
+const data = {
+  foo: {
+    foz: [1, 2, 3],
+    bar: {
+      baz: ['a', 'b', 'c']
+    }
+  },
+  name: null,
+  isDark: false
+};
+deepGet(data, ['foo', 'foz', index]); // get 3
+deepGet(data, ['foo', 'bar', 'baz', 8, 'foz']); // undefined
+deepGet(data, ['name']); // null
+deepGet(data, ['isDark']); // false
+```
 ```
 
 ```js
@@ -25,4 +60,4 @@ const data = {
 };
 deepGet(data, ['foo', 'foz', index]); // get 3
 deepGet(data, ['foo', 'bar', 'baz', 8, 'foz']); // null
-```
+```