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. :)

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. :)

• javascript
• set

• 2 You will need a reference to that specific object, not a new object with equal values. – Bergi Commented Oct 4, 2018 at 5:54
• 1 Iterate by Set using eg. forEach and find the reference of deleting value. And then delete that reference. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Ivan Burnaev Commented Oct 4, 2018 at 5:58
• Thank you Bergi and Ivan for kindly replying and sharing your knowledge. I appreciate it very much! :) – Chess Commented Oct 5, 2018 at 6:23

3 Answers 3

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.

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); });

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)