Check if a Set is Empty in JavaScript?

These are the following ways to check whether the given set is empty or not:

1. Using size property - Mostly used

The size property is used to get the size of the set. if it returns 0 then the set will be empty else it has some elements.

let s = new Set();
if (s.size === 0)
    console.log("Empty set")
else console.log("Not empty set")

// Let us add an item to check for a non-empty set
s.add(1);
if (s.size === 0)
    console.log("Empty set")
else console.log("Not empty set")  

Empty set
Not empty set

2. Using Lodash _.isEmpty() Method

The Lodash is JavaScript library, that provide the _.isEmpty() Method, that checks whether the given set is empty or not and returns the boolean value.

Note: The function can take any value as a parameter to check, it is not limited to set only.

const _ = require("lodash");
let s = new Set();
if (_.isEmpty(s) === true)
     { console.log("Empty set") }
else { console.log("Not empty set") }

Output:

Empty set

3. Using Array.from() Method and length Property

The Array.from() method returns an array from any object with a length property. so it helps us to access the length property so that we can check its emptiness. This method does not alt the original object.

let s = new Set();
s.add(1);
if(Array.from(s).length === 0)
{ console.log("Empty set") } 
else {console.log("Not empty set") } 

Not empty set