클로저

    
      function outerFunction() {
        let outerVariable = 'I am from the outer function';

        function innerFunction() {
          console.log(outerVariable);
        }
        return innerFunction;
      }

      const closure = outerFunction();
      closure(); // 출력: I am from the outer function
    
  

    
      function createCounter() {
        let count = 0;

        return function() {
          count++;
          return count;
        };
      }

      const counter = createCounter();

      console.log(counter()); // 출력: 1
      console.log(counter()); // 출력: 2
      console.log(counter()); // 출력: 3
    
  

    
      function createArrayWithClosures() {
        let arr = [];

        for (let i = 0; i < 3; i++) {
          arr[i] = function() {
            console.log(i);
          };
        }
        return arr;
      }

      const closures = createArrayWithClosures();

      closures[0](); // 출력: 0
      closures[1](); // 출력: 1
      closures[2](); // 출력: 2
    
  

    
      function multiply(a) {
        return function(b) {
          return a * b;
        };
      }

      const double = multiply(2);
      console.log(double(5)); // 출력: 10
      console.log(double(10)); // 출력: 20
    
  

    
      function createPerson(name, age) {
        let _name = name;
        let _age = age;

        return {
          getName: function() {
            return _name;
          },
          getAge: function() {
            return _age;
          },
          setName: function(newName) {
            _name = newName;
          },
          setAge: function(newAge) {
            _age = newAge;
          }
        };
      }

      const person = createPerson('John', 30);
      console.log(person.getName()); // 출력: John

      person.setName('Jane');

      console.log(person.getName()); // 출력: Jane
      console.log(person.getAge());  // 출력: 30
    
  

    
      function memoize(fn) {
        const cache = {};

        return function(...args) {
          const key = JSON.stringify(args);
          if (cache[key]) {
            return cache[key];
          }
          const result = fn(...args);
          cache[key] = result;
          return result;
        };
      }

      function slowFunction(num) {
        console.log('Computing...');
        return num * 2;
      }

      const memoizedFunction = memoize(slowFunction);

      console.log(memoizedFunction(5)); // 출력: Computing... 10
      console.log(memoizedFunction(5)); // 출력: 10 (캐시에서 결과 가져옴)