generator

const gen = function* () {
	console.log(1);
    yield;
    console.log(2);
    yield;
    console.log(3);
    yield 4;
};

const generator = gen();

generator.next();
-> 1 
-> output: {value: undefined, done: false}

generator.next();
-> 2
-> output: {value: undefined, done: false}

// 중단점인 yield 뒤에 값을 넣어주면 value 값으로 리턴된다.
generator.next();
-> 3
-> output: {value: 4, done: false}

generator.next();
-> output: {value: undefined, done: true}

let i = 0;
const gen = generator*() {
	while(true) {
    	yield i++;
    }
}

gen().next();
-> output: {value: 0, done: false}

gen().next();
-> output: {value: 1, done: false}

gen().next();
-> output: {value: 2, done: false}

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