Add key and value interceptor function to manipulate this values

README.md

@@ -159,17 +159,33 @@ flatten({
 // }
 ```
 
+### Key interceptor for flatten
+
+Give the possibility to manipulate the key (Ex: Translate)
+
+``` javascript
+var flatten = require('flat')
+var data = { name: 'Rodolfo', age: 29 };
+
+flatten(data, { maxDepth: 2, keyInterceptor: key => I18n.t(`myModule.${key}`) })
+
+// {
+//   'Nome completo': 'Rodolfo',
+//   'Idade': 29
+// }
+```
+
 ## Command Line Usage
 
-`flat` is also available as a command line tool. You can run it with 
+`flat` is also available as a command line tool. You can run it with
 [`npx`](https://ghub.io/npx):
 
 ```sh
 npx flat foo.json
 ```
 
 Or install the `flat` command globally:
- 
+
 ```sh
 npm i -g flat && flat foo.json
 ```

index.js

@@ -23,9 +23,19 @@ function flatten (target, opts) {
         type === '[object Array]'
       )
 
-      var newKey = prev
-        ? prev + delimiter + key
-        : key
+      var newKey = key
+
+      if (opts.keyInterceptor) {
+        newKey = opts.keyInterceptor(newKey)
+      }
+
+      if (opts.valueInterceptor) {
+        value = opts.valueInterceptor(newKey, value)
+      }
+
+      newKey = prev
+        ? prev + delimiter + newKey
+        : newKey
 
       if (!isarray && !isbuffer && isobject && Object.keys(value).length &&
         (!opts.maxDepth || currentDepth < maxDepth)) {

test/test.js

@@ -510,4 +510,46 @@ suite('Arrays', function () {
       }
     })
   })
+
+  test('Should be translate the keys', function () {
+    var originalData = {
+      name: 'Rodolfo', age: 27
+    };
+
+    var expectedData = {
+      'Nome': 'Rodolfo',
+      'Idade': 27
+    };
+
+    var translates = {
+      name: 'Nome',
+      age: 'Idade'
+    };
+
+    var options = {
+      keyInterceptor: function(key) {
+        return translates[key];
+      }
+    }
+
+    assert.deepEqual(flatten(originalData, options), expectedData);
+  })
+
+  test('Should be sum the value', function () {
+    var originalData = {
+      name: 'Rodolfo', age: 20
+    };
+
+    var expectedData = {
+      name: 'Rodolfo', age: 50
+    };
+
+    var options = {
+      valueInterceptor: function(key, value) {
+        return key === 'age' ? value + 30 : value
+      }
+    }
+
+    assert.deepEqual(flatten(originalData, options), expectedData);
+  })
 })