What is undefined in under code

Question

https://code.sololearn.com/Wj5DKUSUWKOQ/?ref=app

Answer 1

The undefined seems to be just a place holder for the global object. According to the note below you could have used (null, undefined or a primitive value).

"Note that this may not be the actual value seen by the method: if the method is a function in non-strict mode code, null and undefined will be replaced with the global object, and primitive values will be boxed. This argument is required." MDN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

https://code.sololearn.com/WzQ908T6K8kp/#js

Answer 2

Your code :
```
let sum = function(a, b) { console.log(a + b); } sum.apply(undefined, [1, 2]); // 3
```

There should be a semicolon after body of anonymous function (which you are assigning to variable sum).

Javascript applies automatic semicolon insertion after a line break but not in all cases.

In case of assignment it will not insert a semicolon if there is no line break.

Example,
let a = 5, b;

Here you initialize `a` and define b. Javascript expects "a semicolon" or "a line break" or "a valid identifier" after let a = 5,
The same applies to your code.

Correct :
+Use semicolon ;
```
let sum = function(a, b) { console.log(a + b); }; sum.apply(undefined, [1, 2]); // 3
```

+Or use line break
```
let sum = function(a, b){
console.log(a + b);
}

sum.apply(undefined, [1, 2]); // 3
```