this gist explains function hoisting in javascript

hoisting.js

(function () {
  function foo() {
    console.log('foo');
  }

  function bar() {
    console.log('bar');
  }

  function hoistMe() {
    console.log(typeof foo); // outputs "function"
    console.log(typeof bar); // outputs "undefined"

    foo(); // runs normally
    bar(); // gives an error (calling undefined)

    // this one is hoisted: typeof and function call work correctly
    function foo() {
      console.log('local foo');
    }

    // this one is not hoisted!
    var bar = function() {
      console.log('local bar');
    }
  }

  hoistMe();
}());