Coding Diary - Day Two

My plan today wasn't succeeded, I hope I can finished a 6 hours class, but I only finished 70% of it. Although I already use 1.25-time speed to watch the video. What I learned is forEach, find, filter, map, reduce, every, some, all of them is the high order function from ES6. After I watched the video my concept become more clear. The "reduce" method is a bit difficult for me, the question I want to ask the instructor are here :

 (1) Why I can't use "this" in this code?

const profile = { 
    name: 'Alex', 
    getName: function() {               
 return this.name;     } }; 
profile.getName(); 
 
const profile = { 
    name: 'Alex', 
    getName: ()=> {               
 return this.name;} }; 
profile.getName(); 

(2)Are all the function with call back function are an asynchronous function?

(3) How to build a function it's functionality same as "forEach" etc.