https://alligator.io/js/generator-functions-es6/

id-gen.js

/*  ID Generator:
 *
 *  You can use an infinite while in a generator function to create
 *  a function that will generate a new ID every time next() is called on it. 
 *  In this case the infinite loop is not dangerous 
 *  because it will only execute once with calls to next().
 *
 */

function* idGen(){
  let i = 0;
  while (true) {
    yield ++i;
  }
}

const myIdGen = idGen();

console.log(myIdGen.next().value); // 1
console.log(myIdGen.next().value); // 2
console.log(myIdGen.next().value); // 3
console.log(myIdGen.next().value); // 4