CODEWITHSUNDEEP
javascriptset
Chess
Chess

Reputation: 69

How to delete an object from a Set in JavaScript

I would appreciate assistance regarding how to remove/delete a specific object from a Set in JavaScript. I have not been able to find the answer to this seemingly simple question online. Please see the following simple example Set: 

let mySet = new Set([1, 2, {Name: "Ann"}]);

Set(3) {1, 2, {…}}



mySet.delete(1);  

console.log(mySet);

Set(2) {2, {…}}

// The basic syntax above doesn't seem to delete an object within a Set. I have tried the following, none of which removed the object: 

mySet.delete({"Name": "Ann"});
false

mySet.delete("Name");
false

mySet.delete("Ann");
false

Is there a different approach that will remove a specific object from a Set in JavaScript? Perhaps a for...of loop, but then how to specify the specific object for removal? Any help would be greatly appreciated. :)

Upvotes: 6

Views: 10196

Answers (3)

Mudlabs
Mudlabs

Reputation: 579

If you're able to initialise the object before passing it to Set. And retain reference to is (i.e. scope);

const person = { name: "Ann" };
const my_set = new Set([1, 2, person]);
my_set.has(person); //true
my_set.delete(person);
my_set.has(person); // false

Otherwise;

const my_set = new Set([1, 2, { name: "Ann" }]);
my_set.forEach(item => { if (item.name === "Ann") my_set.delete(item); });

Upvotes: 5

naranjja
naranjja

Reputation: 85

What I usually do is,

  1. Convert the Set into an Array
  2. Filter the object out of there using a stringified comparison*
  3. Convert the Array back into a Set

* Careful since this considers order of keys.

You can use this function:

function removeObjectFromSet (set, obj) {
    return new Set([...set].filter((el) => JSON.stringify(el) != JSON.stringify(obj)))
}

For example, like this:

let mySet = new Set([1, 2, { Name: "Ann" }])

mySet = removeObjectFromSet(mySet, { Name: "Ann" })
console.log(mySet)

Upvotes: 1

Akrion
Akrion

Reputation: 18525

The Set object lets you store unique values of any type, whether primitive values or object references.

So this will simply add 2 objects to Set since they do not have the same object references. 

var mySet = new Set([{Name: "Ann"}, {Name: "Ann"}]);

console.log(mySet.size) // 2

You might as well use an array in this case.

So in this scenario to remove Ann (since we do not have an object reference) we would have to:

var mySet = new Set([1, 2, "abc", {Name: "Ann"}]);

console.log('With Ann size:', mySet.size)

mySet.forEach(x => x.Name === 'Ann' ? mySet.delete(x) : x)

console.log('Bye Ann size:', mySet.size)

Now consider this:

var ann = {Name: 'Ann'}
var mySet = new Set([ann, ann])

console.log('With Ann size:', mySet.size)

mySet.delete(ann)

console.log('Bye Ann size:', mySet.size)

So as you can see we are now dealing with object references and firstly the size is only 1 and the Set can now find ann reference and remove it with no issues.

Upvotes: 9

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