JavaScript -- Arrow Function

References:

1. https://www.nczonline.net/blog/2013/09/10/understanding-ecmascript-6-arrow-functions/
2. https://rainsoft.io/when-not-to-use-arrow-functions-in-javascript/
3. http://exploringjs.com/es6/ch_arrow-functions.html
4. https://javascriptweblog.wordpress.com/2010/07/12/understanding-javascript-arrays/
5. https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Functions/Arrow_functions
6. https://www.typescriptlang.org/docs/handbook/functions.html
7. http://www.codebelt.com/typescript/arrow-function-typescript-tutorial/
8. https://basarat.gitbooks.io/typescript/docs/arrow-functions.html#arrow-functions

javascript closure and iify:

1. https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Functions
2. http://javascriptissexy.com/understand-javascript-closures-with-ease/ (closure)
3. https://www.w3schools.com/js/js_function_closures.asp (closure
4. https://www.w3schools.com/js/js_function_invocation.asp 
5.  
6. https://medium.com/@madasamy/15-javascript-concepts-that-every-nodejs-programmer-must-to-know-6894f5157cb7 (javascrpt advance concept)

Closures

• https://www.w3schools.com/js/js_function_closures.asp  (******************** see all example specially last one)

var add = (function () {
  var counter = 0;
  return function () {counter += 1; return counter}
})();

add();
add();
add()