Generator function for infinite loading things

infinite-load-generator.js

// See demo here: https://jsfiddle.net/ccnokes/xfu3yzce/

/* fake request for remote data */
function request(offset = 0) {
  return new Promise((res) => {
    let data = new Array(5).fill(offset).map((n, i) => n + i);
    setTimeout(() => res({ total: 20, data }), 1000);
  });
}

// why a generator? It has an easy built-in api for controlling it and it's closure can hold the bookkeeping details
function* infiniteLoad() {
  let offset = 0;
  let total = Infinity; // set it to max until we know it from first response 
  while(offset < total) {
    yield request(offset)
      .then(res => {
      	total = res.total;
        offset += res.data.length;
        return res;
      });
  }
  return { offset, total };
}

// test it out...
async function test() {
  for await(let item of infiniteLoad()) {
    console.log(item);
  }
}
test();