Function Declaration vs Function Expression

Function Declaration vs Function Expression

// What the difference between:

function declaration() {}; // This is a function declaration

// and

var expression = function() {}; // This is a function expression

// The function declaration is hoisted, definition and all.
// In the expression, only the var declaration is hoisted.
// The assignment of the anonomous function to that variable
// doesn't occur until the line on which the assignment
// occurs.

(function() {

  var func = function() {
    console.log('\tI came from an expression');
  }
  function func() {
    console.log('\tI came from a declaration');
  }
  console.log('What will this print?');
  func();
})();

// Although the func declaration came after the func
// expression, it was hoisted with its definition. So, the
// func expression definition actually comes after the func
// declaration in execution.

// Therefore, function declarations can be invoked before they are
// defined in the document. They will be hoisted on execution.
(function() {

  console.log('Will declaration be invoke?');
  declaration ? declaration() : console.log('\tNot gonna happen');

  function declaration() {
    console.log('\tOh Yeah!');
  }

})();

// What about expression?
(function() {

  console.log('Will expression be invoked?');
  expression ? expression() : console.log('\tNoper');

  var expression = function() {
    console.log('\tYepper');
  }

})();

// What about the combination?
(function() {

  console.log('Will combo be called here?');
  combo ? combo() : console.log('\tApparently Not')

  var combo = function combo(who) {
    console.log('\tI done been called');
  }

  console.log('What about here?');
  combo ? combo() : console.log('\tOh no, Uh Oh');
})();