Question

I’m finding myself by Javascript’s variable scope, could someone explain to me why the first example doesn’t work but the second does?

function test() {
  return typeof(the_variable) !== 'undefined' && the_variable;
}

(function () {
   var the_variable = "doesn't work";
   console.log(test());
}());

var the_variable = "does work";
console.log(test());

Output I get in my log:

false
does work

Also I would like to know how to do something similar to the first example.

Answer 1

Explained in comments:

function test() {
  return typeof(the_variable) !== 'undefined' && the_variable;
}

// The variable in this function is scoped to the anonymous function.
// It doesn't exist outside that function, so `test` cannot see it
(function () {
   var the_variable = "doesn't work";
   console.log(test());
}());

// This variable exists in a scope that wraps the `test` function, so it can see it.
var the_variable = "does work";
console.log(test());