CODEWITHSUNDEEP
javascriptiife
cooljser
cooljser

Reputation: 23

Why second console.log output is the function body rather than 20?

(function b() {
  console.log(b);
  b = 20;
  console.log(b);
})();

I wrote this JavaScript IIFE.
The first console.log logs the function body.
Then the b variable is created with value 20.
The second console.log also logs the function body.
Why not 20?

Upvotes: 2

Views: 79

Answers (1)

Nicholas Tower
Nicholas Tower

Reputation: 85022

Because b is constant and cannot be assigned to. You're in non-strict mode, so the assignment just silently does nothing, but if you use strict mode you will get an error, highlighting the problem.

(function b() {
  'use strict';
  console.log(b);
  b = 20;         // Throws an exception
  console.log(b); // Never gets to here
})();

Upvotes: 6

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