Explain this code

Question

function abc(a){
return (function (y){
return y+1;
})
(++a)+a;
}
console.log(abc(2));

Answer 1

1. abc function is declared.
2. Then we call it and pass 2 as an argument.
3. Inside of abc function parameter a is incremented (it becomes 3) and passed to an immediately called anonymous function (so called IIFE).
4. Then inside of the anonymous function y+1 is evaluated (3+1=4) and returned.
5. Then parameter a (which is 3) is added to the returned value of the anonymous function (which is 4)
6. As a result abc function returns 7 and it is passed to console.log()
7. So, the console output will be 7.