fem-JavaScriptTheHardParts-ClosuresSolutions.js

// CHALLENGE 1 //

function createFunction() {
	return function(){ 
  	console.log('hello');
  }
}

// UNCOMMENT THESE TO TEST YOUR WORK!
var function1 = createFunction();
function1();

///////////////////////////////////////////////////////////////////////////

// CHALLENGE 2 //

function createFunctionPrinter(input) {
  return function(){
    console.log(input);
  }

}

// UNCOMMENT THESE TO TEST YOUR WORK!
var printSample = createFunctionPrinter('sample');
printSample();
var printHello = createFunctionPrinter('hello');
printHello();

///////////////////////////////////////////////////////////////////////////

// CHALLENGE 3 //

//follow the instructions to solve this problem. Look back at the video if you are unsure of why this is occurring. 

///////////////////////////////////////////////////////////////////////////

// CHALLENGE 4 //

function addByX(x) {
	return function(y){
    return x+y;
  }
}

var addByTwo = addByX(2);


// now call addByTwo with an input of 1
console.log(addByTwo(1)) //--> 3

// now call addByTwo with an input of 2
console.log(addByTwo(2)) //--> 4

///////////////////////////////////////////////////////////////////////////

// EXTENSION: CHALLENGE 5 //

function once(func) {
  let called;
  let executed = false;
  return function(num){
    if (executed === false) {
      called = func(num);
    	executed = true;
    } 
    return called;
  }
}

var onceFunc = once(addByTwo);

// UNCOMMENT THESE TO TEST YOUR WORK!
console.log(onceFunc(4));  //should log 6
console.log(onceFunc(10));  //should log 6
console.log(onceFunc(9001));  //should log 6

///////////////////////////////////////////////////////////////////////////

// EXTENSION: CHALLENGE 6 //

function after(count, func) {
	let callMe = 1;
  return function(){
    if (callMe < count) {
      callMe++;
      return callMe
    } else {
      func();
    } 
  }
}

var called = function() { console.log('hello') };
var afterCalled = after(3, called);

afterCalled(); // -> nothing is printed
afterCalled(); // -> nothing is printed
afterCalled(); // -> 'hello' is printed


///////////////////////////////////////////////////////////////////////////

// EXTENSION: CHALLENGE 7 //

function delay(func, wait) {
	setTimeout(func, wait);
}

function displayTwo() { console.log(2) };
delay(displayTwo, 3000); //--> displays 2 after 3000 milliseconds (3 seconds)