Quickest way to update an object's value in an Array

Question

Trying to find out the quickest way to update an object's value in the array.

You wouldn't know the exact position, hence doing animes[0]readStatus=true is not possible
I'm trying to avoid for loop as the array may be A LOT. Example 1 million. Though it seems that for loop is faster, tested by someone and posted here in Medium

Following is my solution to tackle this, could you suggest something better?

const animes = [
  {
    id:'1',
    title:'latest anime',
    readStatus:false,
    imageSource:'https://help.twitter.com/content/dam/help-twitter/twitter-logo.png'
  },
  {
    id:'2',
    title:'naruto',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  },
    {
    id:'3',
    title:'one piece',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  },
    {
    id:'4',
    title:'you name it',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  }
]

let rebels = animes.filter((anime) => {
  return anime.id === '1';
});

let newItems = animes.filter((anime) => {
  return anime.id !== '1';
});


let myMap = Object.assign({}, rebels)
myMap[0].readStatus = true;
newItems.push(myMap[0])
console.log(newItems);

The real question is, why would you even load an array with a million entries on the client side. — Terry
– Terry, Commented Aug 12, 2020 at 14:53
@Terry 'A million' entries is just being exaggeration here. I thought for loop may not be wise to use — Tommy Leong
– Tommy Leong, Commented Aug 12, 2020 at 14:54
Because returning a million records to a user is not useful. It is over whelming — Taplar
– Taplar, Commented Aug 12, 2020 at 14:55
well only way is to loop to find the index. Either for loop or find or make a map. — epascarello
– epascarello, Commented Aug 12, 2020 at 14:55
But aside from that, mapping your array to an object, where they keys are the id of the nested objects, would allow you to do quick look ups from that point on. — Taplar
– Taplar, Commented Aug 12, 2020 at 14:55

Taplar · Accepted Answer · 2020-08-12 14:57:54Z

2

const animeById = animes.reduce((all, anime) => { all[anime.id] = anime; return all; }, {});

You can construct a secondary object with the ids as the key, and then use that going forward for fast lookups.

answered Aug 12, 2020 at 14:57

Taplar

25k4 gold badges24 silver badges36 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

M0nst3R Over a year ago

It's worth noting that aside from the insignificant extra intitial processing required to add this object, it should be maintained everytime elements are added to the array.

inorganik · Accepted Answer · 2020-08-12 14:59:46Z

1

If you are dealing with an array, a loop is the best way to find something. If it's a million items, sounds like you need to consider your database strategy!

But that aside, here's how I would do it:

const animes = [
  {
    id:'1',
    title:'latest anime',
    readStatus:false,
    imageSource:'https://help.twitter.com/content/dam/help-twitter/twitter-logo.png'
  },
  {
    id:'2',
    title:'naruto',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  },
    {
    id:'3',
    title:'one piece',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  },
    {
    id:'4',
    title:'you name it',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  }
]

function markAsRead(id) {
  const idx = animes.findIndex(a => a.id === id);
  if (idx > -1) {
    animes.splice(idx, 1, { ...animes[idx], readStatus: true });
  }
}

markAsRead('1');

console.log(animes);

answered Aug 12, 2020 at 14:59

inorganik

25.7k18 gold badges96 silver badges126 bronze badges

1 Comment

Tommy Leong Over a year ago

I have to admit, I was being exaggeration with my question for saying A Million records will be stored in the array. As mentioned on the comment earlier, I thought it may not be wise to use for loop to update the object's value. Thanks for the suggestion, it does better job than mine (:

BananZ · Accepted Answer · 2021-02-08 04:21:59Z

Am i late to join the party?

As JS's array is storing a list of references, the easiest way is to find the first matching object, and update it straight away. This will alter the original object from the list itself. There is no need to modify / recreate the list.

const animes = [
  {
    id:'1',
    title:'latest anime',
    readStatus:false,
    imageSource:'https://help.twitter.com/content/dam/help-twitter/twitter-logo.png'
  },
  {
    id:'2',
    title:'naruto',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  },
    {
    id:'3',
    title:'one piece',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  },
    {
    id:'4',
    title:'you name it',
    readStatus:true,
    imageSource:'https://mapstr-prod.s3.amazonaws.com/298ed6c57ada2a7560d24dabba452548_facebook-logo-F-1200x816.jpg'
  }
]

const target = animes.find(e=>e.id==='1');
target && (target.readStatus = true);


console.log(JSON.stringify(animes, null, 2));

Collectives™ on Stack Overflow

Quickest way to update an object's value in an Array

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related