functions.js

// ==== Callbacks ====  

/* Step 1: Create a higher-order function that accepts a callback
  * Create a higher-order function named consume that can take 3 parameters.
  * The first two parameters can accept any argument
  * The last parameter accepts a callback 
  * In the body of the function return the callback with the two parameters that you created
*/
function consume(x, y, cb) {
  return cb(x, y)
}

/* Step 2: Create several functions to callback with consume();
  * Create a function named add that returns the sum of two numbers
  * Create a function named multiply that returns the product of two numbers 
  * Create a function named greeting that accepts a first and last name and returns "Hello first-name last-name, nice to meet you!"
*/
function add(x, y) {
  return x + y
};
function multiply(x, y) {
  return x*y
};
function greeting(first_name, last_name){
  return `Hello ${first_name} ${last_name}, nice to meet you!`
}
/* Step 3: Check your work by un-commenting the following calls to consume(): */
consume(2,2,add); // 4
consume(10,16,multiply); // 160
consume("Mary","Poppins", greeting); // Hello Mary Poppins, nice to meet you!


// ==== Closures ==== 

// Explain in your own words why `nestedfunction()` can access the variable `internal`.

// Explanation: 
// because the variable internal was created in the global scope of the function, giving the entire function access to it

const external = "I'm outside the function";

function myFunction() {
  console.log(external);
  const internal = "Hello! I'm inside myFunction!";

  function nestedFunction() {
    console.log(internal);
  };
  nestedFunction();
}
myFunction();