What is WeakSet Object in JavaScript?

Javascript Web Development Front End Technology

In this article, we are going to explore WeakSet objects and how to use them in JavaScript. The JavaScript WeakSet object is a type of collection that allows the user to store items that are held loosely only.

WeakSet is just a collection of items that do not include any arbitrary values.
It has the same feature as that of a set and does not contain any duplicates.
The main difference between the WeakSet and a Set is that a WeakSet is a collection of Objects rather than values of a certain type.
It supports the following functions: add, has, delete.

Syntax

new WeakSet([iterable])

Parameter

iterable − This is an iterable object which will hold the elements that need to be added to the set.

Advantages of using a WeakSet Object

The contents of a weak set are garbage collected.
It lowers the memory utilization when properly used.
It is very useful for class branding.

Features of a WeakSet Object

It consists of unique elements only.
Elements will automatically be garbage collected if no references are stored in the weak set.
Items in a weak set are not enumerable.
It supports the add, has, and delete functions like a set, but does not support size, keys, and iterations function.

WeakSet Methods

add() − This method adds/appends values to the weak set.
has(value) −This method checks if the weak set has/contains the passed value or not.
delete(value) − This method removes a value from the WeakSet.

Example 1

In this example, we are going to use the methods from the weak set and see how to use it in various cases.

#Filename: index.html

<!DOCTYPE html>
<html lang="en">
<head>
   <title>WeakSet</title>
</head>
<body>
   <script>
      const welcome = {"key": "value"};
      const tutorialspoint = {"title": "tutorialspoint"}
      const weak_set = new WeakSet([welcome, tutorialspoint]);
      
      // Checking if tutorialspoint exists
      document.write("Is tutorialspoint exists: " + weak_set.has(tutorialspoint));
   </script>
</body>
</html>

Output

It will produce the following output.

Is tutorialspoint exists: true

Example 2

#Filename: index.html

<!DOCTYPE html>
<html lang="en">
<head>
   <title>WeakSet</title>
</head>
<body>
   <script>
      const weak_set = new WeakSet();
      const welcome = {"key": "value"};
      const tutorialspoint = {"title": "tutorialspoint"}
      
      //Adding object to weakset
      weak_set.add(welcome);
      weak_set.add(tutorialspoint);
      
      // Deleteing an object
      weak_set.delete(tutorialspoint);
      document.write("Is tutorialspoint exists: " + weak_set.has(tutorialspoint));
   </script>
</body>
</html>