snippet.js

/*
So, I struggled with the logic of - given we have 2 or 3 arrays, what items exist in ALL 3
Idea by @falken on Masto
*/
let numArrays = 0;
if(filter.title) numArrays++;
if(filter.duration) numArrays++;
if(filter.ingredient) numArrays++;
let idBag = {};
let obBag = {};

if(filter.title) {
  for(t of byTitle) {
    if(!idBag[t.id]) idBag[t.id] = 1;
    else idBag[t.id]++;
    obBag[t.id] = t;
  }
}
if(filter.duration) {
  for(t of byDuration) {
    if(!idBag[t.id]) idBag[t.id] = 1;
    else idBag[t.id]++;
    obBag[t.id] = t;
  }
}
if(filter.ingredient) {
  for(t of byIngredient) {
    if(!idBag[t.id]) idBag[t.id] = 1;
    else idBag[t.id]++;
    obBag[t.id] = t;
  }
}

for(let id in idBag) {
  if(idBag[id] === numArrays) result.push(obBag[id]);
}

resolve(result);