how to get the cardinality of a set in javascript

To get the number of elements in a Set object in JavaScript, you can use the size property or the size method. Here's an example:

index.tsx
const mySet = new Set([1, 2, 3, 2, 1]);
console.log(mySet.size); // Output: 3
78 chars
3 lines

In this example, we create a Set mySet that contains four elements, but two of them are duplicates. The size property of mySet returns the number of distinct elements, which is 3.

Alternatively, you can use the size method to achieve the same result:

index.tsx
const mySet = new Set([1, 2, 3, 2, 1]);
console.log(mySet.size()); // Output: 3
80 chars
3 lines

Note that the size method is a function, whereas the size property is not.