adds block about angular low-level functions

Update README.md

Update README.md

Addressed comments made in #768

Low level functions: added code samples and more why's

Angular Helper Functions: more reviews in #768

Angular Helper Functions: addressing more comments on #768

Author: sergiocruz

a1/README.md

@@ -56,6 +56,7 @@ While this guide explains the *what*, *why* and *how*, I find it helpful to see
   1. [Routing](#routing)
   1. [Task Automation](#task-automation)
   1. [Filters](#filters)
+  1. [Low Level Functions](#low-level-functions)
   1. [Angular Docs](#angular-docs)
 
 ## Single Responsibility
@@ -3268,6 +3269,98 @@ Use [Gulp](http://gulpjs.com) or [Grunt](http://gruntjs.com) for creating automa
 
 **[Back to top](#table-of-contents)**
 
+## Helper Functions
+
+Angular 1.x ships with some [helper functions](https://docs.angularjs.org/api/ng/function) that are found within JavaScript natively (e.g. `angular.isArray()`, `angular.forEach()`, etc). In such cases we should favor usage of native JavaScript functions instead of Angular's helper functions. In other cases where functionality is not found in JavaScript natively, we should turn to utility libraries such as [lodash](https://lodash.com/docs) to fill-in the gaps.
+
+###### [Style [Y500](#style-y500)]
+
+  - Avoid using Angular helper functions such as `angular.copy()`, `angular.extend()` or even `angular.isUndefined()`.
+
+  *Why?*: You can replace a of lot Angular's helper functions with native ES2015+ functionality such as [`Object.assign()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign) for copying objects and the [Spread Syntax](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator#Copy_an_array) for copying arrays _(ie. `[...arr1]`)_.
+
+  *Why?*: Because these are features that have been made available in the latest versions of JavaScript, but did not exist natively when the Angular helper functions were first written.
+
+  Replace `angular.forEach()` and `angular.isArray()`:
+
+  ```javascript
+  /* avoid */
+  var arr = [1, 2, 3];
+  var obj = { hello: 'Hello', world: 'World' };
+
+  angular.forEach(arr, function(value) {
+    console.log(value);
+  });
+
+  angular.forEach(obj, function(value) {
+    console.log(value);
+  });
+
+  angular.isArray(arr); // true
+  angular.isArray(obj); // false
+  ```
+
+  ```javascript
+  /* recommended */
+  var arr = [1, 2, 3];
+  var obj = { hello: 'Hello', world: 'World' };
+
+  // iterate through arrays
+  arr.forEach(function(value) {
+    console.log(value);
+  });
+
+  // iterate through objects
+  Object.keys(obj)
+    .forEach(function(key) {
+      console.log(obj[key]);
+    });
+
+  // alternative lodash helper to iterate through objects
+  _.forEach(obj, function(value) {
+    console.log(value);
+  });
+
+  // native js functionality
+  Array.isArray(arr); // true
+  Array.isArray(obj); // false
+  ```
+
+  Favor usage of JavaScript features (in this case available starting with ES2015) over `angular.copy()` and `angular.extend()`.
+
+  ```javascript
+  /* avoid */
+  var arr1 = [1, 2, 3];
+  var arr2 = angular.copy(arr1); // [1, 2, 3]
+
+  var obj1 = { hello: 'Hello' };
+  var obj2 = { world: 'World' };
+  var obj3 = angular.extend({}, obj1, obj2); // {hello: 'Hello', world: 'World'}
+  ```
+
+  ```javascript
+  /* recommended */
+  var arr1 = [1, 2, 3];
+  var arr2 = [...arr1]; // [1, 2, 3]
+
+  var obj1 = { hello: 'Hello' };
+  var obj2 = { world: 'World' };
+  var obj3 = Object.assign({}, obj1, obj2); // {hello: 'Hello', world: 'World'}
+  ```
+
+  *Why?*: These are commonly known features of JavaScript and using them makes code more intuitive to read.
+
+  *Why?*: This will ease the process of upgrading to Angular 2 as it does not ship with these helper functions.
+
+
+  - Note: favor usage of functions that are available in JavaScript natively, then resort to using a utility library like [lodash](https://lodash.com/docs) when what you need is not available.
+
+  - Note: you might need to use a [polyfill](https://babeljs.io/docs/usage/polyfill/) to take advantage of the latest features of JavaScript for better browser support.
+
+  - Note: Be sure to understand the differences in implementation when using a native JavaScript feature over an Angular helper. For example Angular's `forEach` implementation does not throw an error if you pass it a `null` or `undefined` object, whereas JavaScript's native implementation only works with arrays.
+
+**[Back to top](#table-of-contents)**
+
 ## Filters
 
 ###### [Style [Y420](#style-y420)]