finishingGenerators.js

function* customGenerator() {
  yield 1;
  yield 2;
  yield 3; 
}

let getIterator = customGenerator();

let nextValue = null;

nextValue = getIterator.next();
console.log(nextValue);  
// Output is: { value: 1, done: false }

nextValue = getIterator.next();
console.log(nextValue);  
// Output is: { value: 2, done: false }

nextValue = getIterator.next();
console.log(nextValue);  
// Output is: { value: 3, done: false }

nextValue = getIterator.next();
console.log(nextValue);  
// Output is: { value: undefined, done: true }