Self-propelled shooter functions

[briley]

Tell me what the difference is and why doesn't it work?

var obj = {
  a: 10,
  b: (function() {
    return this.a
  })()
}
console.log(obj);
var obj = {

a: 10,

b: (() => {

this.a

})()

}

console.log(obj);

[kalyn]

var obj = { a: 10, b: (function () { return 20; }() }

Is such a code available to shooters? Principal condition becomes that the function must be self-induced

//var obj = { a: 10, b: (function () { return 20; }()) } 
var obj = { a: 10, b: (() => 20)() };
console.log(obj);