Chapter 04.txt

(function autorun(){
    let x = 1;
    function log(){ 
       console.log(x); 
    }
    log();
})();


(function autorun(){
    let x = 1;
    function log(){
      console.log(x);
    };
    
    function run(fn){
      let x = 100;
      fn();
    }
    
    run(log); //1
})();


(function autorun(){
  let x = 1;
  setTimeout(function log(){
    console.log(x);
  }, 10000);
})();


(function autorun(){
  let x = 1;
  $("#btn").click(function log(){
    console.log(x);
  });
})();


(function autorun(){
  let x = 1;
  fetch("/todos").then(function log(){
    console.log(x);
  });
})();

//--------------------

function* sequence(){
  let count = 0;
  while(true) {
    count += 1;
    yield count;
  }
}

const generator = sequence();
generator.next().value; //1
generator.next().value; //2
generator.next().value; //3

//--------------------

function sequence(){
  let count = 0;
  return function(){
    count += 1;
    return count;
  }
}

const generator = sequence();
generator(); //1
generator(); //2
generator(); //3

//--------------------

const counter = (function(){
    let state = 0;
    
    function increment(){
       state += 1;
       return state;
    }
    
    function decrement(){
       state -= 1;
       return state;
    }
    
    return {
       increment,
       decrement
    }
})();

counter.increment(); //1
counter.increment(); //2
counter.decrement(); //1

//--------------------

//module "./counter.js"
let state = 0;

function increment() {
  state += 1;
  return state;
}

function decrement() {
  state -= 1;
  return state;
}

export default {
  increment,
  decrement
}

//module "./index.js"
import counter from "./counter";

counter.increment(); //1
counter.increment(); //2
counter.decrement(); //1