67.if.md

67. if

Problem

https://bigfrontend.dev/quiz/if

Problem Description

What does the code snippet below output by console.log?

if (true) {
  function foo() {
    console.log('BFE');
  }
}
if (false) {
  function bar() {
    console.log('dev');
  }
}

foo();
bar();

Answer

if (true) {
  function foo() {
    console.log('BFE');
  }
}
if (false) {
  function bar() {
    console.log('dev');
  }
}

// In Chrome and Firefox:
foo(); // 'BFE'
bar(); // Error

// In Safari:
foo(); // 'BFE'
bar(); // 'dev'

Explanation

When we define a function within an if statement, the result varies on browsers. In Chrome and Firefox, only the name of the function is hoisted, whereas in Safari, the function is hoisted.

Reference

Conditionally created functions