difficulty in understanding closures

Question

Why this code returns 43 as the result, I expect it to result 42. The code is as follows:

function say667() {
  // Local variable that ends up within closure
  var num = 42;
  var say = function() { console.log(num); }
  num++;
  return say;
}
var sayNumber = say667();
sayNumber();

Why? Because you call the inner function ***after*** `num` has been incremented — charlietfl, Aug 02 '18 at 21:33

score 4 · Accepted Answer · answered Aug 02 '18 at 21:34

You've closed over the variable num, not the value the variable has at the time you define the function.

This is the order of events:

You assign 42 to num
You increment num to 43
You return a function and store it in sayNumber
You call that function, which reads the value of num, which is 43

difficulty in understanding closures

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