ES6 and Arrow Function Expressions

Javascript’s function expressions before 2015 ECMA Script (ES6) resembled many languages in its syntax:

// Traditional Function Declaration
function plusOneHundred(a){
  return a + 100;
}

Here is a function, plusOneHundred(), and within parentheses an argument, a which is used to return a value a+100. A JavaScript function declaration pre-ES6 is similar to a C++ Constructor, in…