adds deepMapKeys snippet

snippets/deepMapKeys.md

@@ -0,0 +1,59 @@
+### deepMapKeys
+
+Deep maps an object keys.
+
+Creates an object with the same values as the provided object and keys generated by running the provided function for each key.
+
+Use Object.keys(obj) to iterate over the object's keys. Use Array.prototype.reduce() to create a new object with the same values and mapped keys using fn.
+
+```js
+const deepMapKeys = (obj, f) => (
+  Array.isArray(obj)
+    ? obj.map(val => deepMapKeys(val, f))
+    : (typeof obj === 'object')
+    ? Object.keys(obj).reduce((acc, current) => {
+      const val = obj[current];
+      acc[f(current)] = (val !== null && typeof val === 'object')
+        ? deepMapKeys(val, f)
+        : acc[f(current)] = val;
+      return acc;
+    }, {})
+    : obj
+);
+```
+
+```js
+'use strict';
+const obj = {  
+   foo:'1',
+   isnull:null,
+   nested:{  
+      bar:'1',
+      child:{  
+         withArray:[  
+            {  
+               grandChild:[ 'hello' ]
+            }
+         ]
+      }
+   }
+}
+const upperKeysObj = deepMapKeys(obj, (key) => key.toUpperCase());
+/*
+Formatted JSON Data
+{  
+   "FOO":"1",
+   "ISNULL":null,
+   "NESTED":{  
+      "BAR":"1",
+      "CHILD":{  
+         "WITHARRAY":[  
+            {  
+               "GRANDCHILD":[ 'hello' ]
+            }
+         ]
+      }
+   }
+}
+*/
+```