4.md

4-1

var count = 0;
var timer = setInterval(function() {
  console.log(count);
  if (++count > 4) clearInterval(timer);
}, 300);

4-2

var count = 0;
var cbFunc = function() {
  console.log(count);
  if (++count > 4) clearInterval(timer);
};
var timer = setInterval(cbFunc, 300);

// -- 실행 결과 --
// 0  (0.3초)
// 1  (0.6초)
// 2  (0.9초)
// 3  (1.2초)
// 4  (1.5초)

4-3

var newArr = [10, 20, 30].map(function(currentValue, index) {
  console.log(currentValue, index);
  return currentValue + 5;
});
console.log(newArr);

// -- 실행 결과 --
// 10 0
// 20 1
// 30 2
// [15, 25, 35]

4-4

var newArr2 = [10, 20, 30].map(function(index, currentValue) {
  console.log(index, currentValue);
  return currentValue + 5;
});
console.log(newArr2);

// -- 실행 결과 --
// 10 0
// 20 1
// 30 2
// [5, 6, 7]

4-5

Array.prototype.map = function(callback, thisArg) {
  var mappedArr = [];
  for (var i = 0; i < this.length; i++) {
    var mappedValue = callback.call(thisArg || window, this[i], i, this);
    mappedArr[i] = mappedValue;
  }
  return mappedArr;
};

4-6

setTimeout(function() {
  console.log(this);
}, 300); // (1) Window { ... }

[1, 2, 3, 4, 5].forEach(function(x) {
  console.log(this); // (2) Window { ... }
});

document.body.innerHTML += '<button id="a">클릭</button>';
document.body.querySelector('#a').addEventListener(
  'click',
  function(e) {
    console.log(this, e); // (3) <button id="a">클릭</button>
  } // MouseEvent { isTrusted: true, ... }
);

4-7

var obj = {
  vals: [1, 2, 3],
  logValues: function(v, i) {
    console.log(this, v, i);
  },
};
obj.logValues(1, 2); // { vals: [1, 2, 3], logValues: f } 1 2
[4, 5, 6].forEach(obj.logValues); // Window { ... } 4 0
// Window { ... } 5 1
// Window { ... } 6 2

4-8

var obj1 = {
  name: 'obj1',
  func: function() {
    var self = this;
    return function() {
      console.log(self.name);
    };
  },
};
var callback = obj1.func();
setTimeout(callback, 1000);

4-9

var obj1 = {
  name: 'obj1',
  func: function() {
    console.log(obj1.name);
  },
};
setTimeout(obj1.func, 1000);

4-10

var obj1 = {
  name: 'obj1',
  func: function() {
    var self = this;
    return function() {
      console.log(self.name);
    };
  },
};

var obj2 = {
  name: 'obj2',
  func: obj1.func,
};
var callback2 = obj2.func();
setTimeout(callback2, 1500);

var obj3 = { name: 'obj3' };
var callback3 = obj1.func.call(obj3);
setTimeout(callback3, 2000);

4-11

var obj1 = {
  name: 'obj1',
  func: function() {
    console.log(this.name);
  },
};
setTimeout(obj1.func.bind(obj1), 1000);

var obj2 = { name: 'obj2' };
setTimeout(obj1.func.bind(obj2), 1500);

4-12

setTimeout(
  function(name) {
    var coffeeList = name;
    console.log(coffeeList);

    setTimeout(
      function(name) {
        coffeeList += ', ' + name;
        console.log(coffeeList);

        setTimeout(
          function(name) {
            coffeeList += ', ' + name;
            console.log(coffeeList);

            setTimeout(
              function(name) {
                coffeeList += ', ' + name;
                console.log(coffeeList);
              },
              500,
              '카페라떼'
            );
          },
          500,
          '카페모카'
        );
      },
      500,
      '아메리카노'
    );
  },
  500,
  '에스프레소'
);

4-13

var coffeeList = '';

var addEspresso = function(name) {
  coffeeList = name;
  console.log(coffeeList);
  setTimeout(addAmericano, 500, '아메리카노');
};
var addAmericano = function(name) {
  coffeeList += ', ' + name;
  console.log(coffeeList);
  setTimeout(addMocha, 500, '카페모카');
};
var addMocha = function(name) {
  coffeeList += ', ' + name;
  console.log(coffeeList);
  setTimeout(addLatte, 500, '카페라떼');
};
var addLatte = function(name) {
  coffeeList += ', ' + name;
  console.log(coffeeList);
};

setTimeout(addEspresso, 500, '에스프레소');

4-14

new Promise(function(resolve) {
  setTimeout(function() {
    var name = '에스프레소';
    console.log(name);
    resolve(name);
  }, 500);
})
  .then(function(prevName) {
    return new Promise(function(resolve) {
      setTimeout(function() {
        var name = prevName + ', 아메리카노';
        console.log(name);
        resolve(name);
      }, 500);
    });
  })
  .then(function(prevName) {
    return new Promise(function(resolve) {
      setTimeout(function() {
        var name = prevName + ', 카페모카';
        console.log(name);
        resolve(name);
      }, 500);
    });
  })
  .then(function(prevName) {
    return new Promise(function(resolve) {
      setTimeout(function() {
        var name = prevName + ', 카페라떼';
        console.log(name);
        resolve(name);
      }, 500);
    });
  });

4-15

var addCoffee = function(name) {
  return function(prevName) {
    return new Promise(function(resolve) {
      setTimeout(function() {
        var newName = prevName ? prevName + ', ' + name : name;
        console.log(newName);
        resolve(newName);
      }, 500);
    });
  };
};
addCoffee('에스프레소')()
  .then(addCoffee('아메리카노'))
  .then(addCoffee('카페모카'))
  .then(addCoffee('카페라떼'));

4-16

var addCoffee = function(prevName, name) {
  setTimeout(function() {
    coffeeMaker.next(prevName ? prevName + ', ' + name : name);
  }, 500);
};
var coffeeGenerator = function*() {
  var espresso = yield addCoffee('', '에스프레소');
  console.log(espresso);
  var americano = yield addCoffee(espresso, '아메리카노');
  console.log(americano);
  var mocha = yield addCoffee(americano, '카페모카');
  console.log(mocha);
  var latte = yield addCoffee(mocha, '카페라떼');
  console.log(latte);
};
var coffeeMaker = coffeeGenerator();
coffeeMaker.next();

4-17

var addCoffee = function(name) {
  return new Promise(function(resolve) {
    setTimeout(function() {
      resolve(name);
    }, 500);
  });
};
var coffeeMaker = async function() {
  var coffeeList = '';
  var _addCoffee = async function(name) {
    coffeeList += (coffeeList ? ',' : '') + (await addCoffee(name));
  };
  await _addCoffee('에스프레소');
  console.log(coffeeList);
  await _addCoffee('아메리카노');
  console.log(coffeeList);
  await _addCoffee('카페모카');
  console.log(coffeeList);
  await _addCoffee('카페라떼');
  console.log(coffeeList);
};
coffeeMaker();