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Underscore.js _.isWeakSet() Function

  • Last Updated : 10 Jul, 2020

Underscore.js is a JavaScript library that makes operations on arrays, string, objects much easier and handy.
he _.isWeakSet() function is used to check whether the given object is JavaScript weakset or not. When linking the underscore.js CDN, the “_” is attached to the browser as global variable.

Syntax :

_.isWeakSet( object );

Parameters:

  • object: It is any JavaScript object such as array, string, maps, set etc.

Return Value: It returns the boolean value. If the set is a weak set it returns true otherwise returns false.

Example 1: When a weak set is given it returns true.




<!DOCTYPE html>
<html lang="en">
  
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content=
        "width=device-width, initial-scale=1.0">
  
    <script src=
    </script>
</head>
  
<body>
    <script>
  
        // Creating a weak set using
        // constructor
        var obj = new WeakSet();
  
        // Using the _.weakSet() function
        var isWeakSet = _.isWeakSet(obj);
        console.log(isWeakSet)
  
        // If the given object is weakset 
        // it prints the object is weak set.
        if (isWeakSet)
            console.log(`The ${obj} is the 
                    WeakSet of Javascript.`)
        else
            console.log(`The ${obj} is not 
                the WeakSet of Javascript.`)
    </script>
</body>
  
</html>

Output:

Example 2: When an array is given the output is false.




<!DOCTYPE html>
<html lang="en">
  
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content=
        "width=device-width, initial-scale=1.0">
  
    <script src=
    </script>
</head>
  
<body>
    <script>
  
        // Creating a array of size 
        // 2 using constructor
        var obj = new Array(2);
  
        // Filling value 10in the array
        obj.fill(10)
  
        // Using the _.weakSet() function
        var isWeakSet = _.isWeakSet(obj);
        console.log(isWeakSet)
  
        // If the given object is weakset 
        // it prints the object is weak set
        if (isWeakSet)
            console.log(`The ${obj} is the
                WeakSet of Javascript.`)
        else
            console.log(`The ${obj} is not 
                the WeakSet of Javascript.`)
    </script>
</body>
  
</html>

Output:


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