Function returning a function in JavaScript

Let's say we have a function like this that returns a string:

javascriptfunction func() {
  return '!';
}

let result = func();
console.log(result); // shows '!'

Let's now instead of a string, by analogy, return an anonymous function:

javascriptfunction func() {
  return function() {
    return '!';
  };
}

let result = func(); // there will be a function in the variable result
console.log(result); // shows 'function() {return '!';}'

As you can see, the variable result is now a function. Let's display the result of its work in the console. To do this, write parentheses to it:

javascriptfunction func() {
  return function() {
    return '!';
  };
}

let result = func();
console.log( result() ); // shows '!'

Since calling func() returns a function, we can immediately invoke this returned function, like this: func()() - the first parentheses get the result of the function func (which is a function itself), and the second parentheses are applied to the result of func.

Let's try:

javascriptfunction func() {
  return function() {
    return '!';
  };
}

console.log( func()() ); // shows '!'