1-hoisting

Part I: Hoisting

Note: Before getting started on these exercises, please be certain that you've read through the root README.md file in this repository.

In order to complete these exercises, open repl.it, choose JavaScript, and then write your code in the left-hand panel. You can run your code using the "Run" button.

Two Forms of Functions

// function declaration
function square(x) {
  return x * x;
}

// function expression
var square = function(x) {
  return x * x;
};

Exercises

Basic Requirements

Rewrite Functions

Rewrite the following function declarations using a function expression:

// 1.
function cube(x) {
  return x * x * x;
}

// 2.
function fullName(first, last) {
  return first + " " + last;
}

// 3.
function power(base, exp) {
  if (exp === 0) {
    return 1;
  }
  return base * power(base, exp - 1);
}

// 4.
function sumCubes(numbers) {
  var total = 0;
  for (var i = 0; i < numbers.length; i++) {
    total = total + cube(numbers[i]);
  }
  return total;
}

Mechanics of Hoisting

Type out your best answers to the following questions:

1. Why does JavaScript output undefined instead of throwing an error in the following code?

console.log(message);

var message = 'Hi there!';

2. Why does JavaScript throw an error instead of logging undefined in the following code?

   console.log(message);
   
   let message = 'Hi there!';

3. Explain precisely what happens when the following code is executed.

   console.log(showMessage());
   
   var showMessage = function(){
     return 'Hi there!';
   };

4. Why does JavaScript not throw any errors when the following code is executed?

console.log(showMessage());

function showMessage(){
  return 'Hi there!';
}

Code Restructuring

Restructure the following instances of code to work correctly:

// 1.
for(var i = 0; i < values.length; i++){
  console.log(values[i]);
}

var values = [10, 20, 30];

// 2.
console.log(welcome('Charlie', 'Munger'));

function welcome(first, last) {
  return `Welcome, ${first} ${last}! You last logged in on ${lastLogin}.`
};

var lastLogin = '1/1/1970';