Array filter javascript [duplicate]

Question

My goal is to add a multiSelect.

So, I created an object that contains two lists.

events and events_sel

I want to use an event list to fill the checkbox.

and I want to use the events_sel list to mark the selected events, and everything that doesn’t exist in events_sel becomes available in the checkbox.

In the small example below, create an object simulating this situation, but I'm not sure that I can use array filter for this.

Or if you would have to use a loop.

And yet, I was not able to separate the list as in the superficial example inside the filter, below.

const object = {
  events: [
    { id: 1, description: "event 1" },
    { id: 2, description: "event 2" },
    { id: 3, description: "event 3" },
    { id: 4, description: "event 4" },
    { id: 5, description: "event 5" },
  ],
  events_sel: [{ event_id: 1 }, { event_id: 2 }],
};

let events = object.events;
let eventsSel = object.events_sel;

// array filter
events.filter(function (event, i) {
  //console.log(eventsSel[i].event_id)
  if (event.id == 1 || event.id == 2)
    console.log(`Selecionado: ${event.description}`);
  else
    console.log(`Não Selecionado: ${event.description}`);
});

// for
for (const event of events) {
  //console.log(event);
}

My final goal is to replace this excerpt if (event.id == 1 || event.id == 2) with the data that is in the list events_sel

Please edit your post title to ask a clear, specific question. — isherwood
– isherwood, Commented May 18, 2021 at 16:52
The callback function needs to return a boolean that indicates whether to include the element in the result. And it doesn't modify the list in place, it returns a new list, so you need to assign the result. — Barmar
– Barmar, Commented May 18, 2021 at 16:52
Why is events_sel an array of objects instead of an array of IDs? If it were events_sel: [1, 2] you could use if (eventsSel.includes(event.id)) — Barmar
– Barmar, Commented May 18, 2021 at 16:53
With the array of objects, use if (eventsSel.some(el => el.event_id == event.id)) — Barmar
– Barmar, Commented May 18, 2021 at 16:55

Sebastian Simon · Accepted Answer · 2022-11-03 21:08:19Z

1

Use the some method, and assign the result back to events.

const object = {
  events: [
    { id: 1, description: "event 1" },
    { id: 2, description: "event 2" },
    { id: 3, description: "event 3" },
    { id: 4, description: "event 4" },
    { id: 5, description: "event 5" },
  ],
  events_sel: [ { event_id: 1 }, { event_id: 2 } ],
};
let events = object.events;
let eventsSel = object.events_sel;

// Array filter
events = events.filter(function(event, i) {
  // console.log(eventsSel[i].event_id)
  return eventsSel.some((el) => el.event_id == event.id)
});

// for
for (const event of events) {
  console.log(event);
}

edited Nov 3, 2022 at 21:08

Sebastian Simon

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answered May 18, 2021 at 17:09

Barmar

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