FAT ARROW FUNCTIONS =>

For a long time, while learning about Angular 2, ionic 2, Typescript and ECMAScript 2015 (ES6), i had difficulty grasping the concept of fat arrow functions.

i found this tutorial on youtube which helped me alot to learn about fat arrow functions, so this is just a simple functions in javascrip (ES5) and ECMAScript (ES6) on how to use fat arrows

this is the old way format:

var getRegvalue() = function(){
    return 10;
}
console.log(getRegvalue()); // 10

THIS IS THE NEW FAT ARROW FORMAT
const getArrowvalue = () =>{
    return 10;
}
console.log(getRegvalue()); // 10

THIS IS A MORE SHORT AND CONCISE WAY OF DOING THE EXACT SAME FUNCTION AS ABOVE IF THE FUNCTION HAS A SINGLE STATEMENT WITHIN THE BODY THEN YOU CAN REMOVE THE CURLY BRACES
const getArrowvalue = () =>{
return 10;
}

YOU CAN EVEN MAKE IT SHORTER LIKE THIS IF ONLY A SINGLE STATEMENT IS WITHIN THE BODY
const getArrowvalue = () => return 10;

YOU CAN EVEN MAKE IT MORE SHORTER BY REMOVING THE 'return'
const getArrowvalue = () => 10;

PASSING ARGUEMTENS IN FAT ARRROW FUNCTIONS:
const getArrowvalue= (m) => 10*m; // m is a multiplier
console.log(getRegvalue(10)); // returns 100 (10*10)

NOTE: if you are passing a SINGLE argument, you can omit the parentheses
const getArrowvalue= m => 10*m;
console.log(getRegvalue(10)); // return 100 (10*10)

OK, what if you have multiple arguments, here is an example:
const getArrowvalue= (m,bonus) => 10*m+bonus;
console.log(getRegvalue(10,50)); // return 150 (10*10)

to show you that getArrowvalue is really a function, you can use typeof like this:
console.log(typeOf getRegvalue); // function

IF YOU STILL NEED MORE HELP, CHECKOUT THIS VIDEO, IT WAS VERY HELPFUL FOR ME

ES6 and Typescript Tutorial - 10 - Arrow Functions
https://www.youtube.com/watch?v=4N-L3Mmzu0Y&list=PLC3y8-rFHvwhI0V5mE9Vu6Nm-nap8EcjV&index=7

FAT arrow functions are great because of lexicals. and also with ecmascript you can declare default values within a fuction,

just like php, you can setup default paramater in a fuction.
for example:
let (getRegvalue(a=50){
    return a*10;
}