# Useful features of Set collections

`Set` collections have a number of useful properties and methods. Let's take a look at them.

## Collection size

The `size` property contains the size of the collection:

`let set = new Set; set.add(1); set.add(2); set.add(3); console.log(set.size);`

## Checking for a value presence

You can check if a value exists in a collection using the `has` method:

`let set = new Set; set.add(1); set.add(2); set.add(3); console.log(set.has(1));`

## Element deletion

You can delete an element from a collection using the `delete` method:

`let set = new Set; set.add(1); set.add(2); set.add(3); set.delete(1);`

## Clearing a collection

You can clear an entire collection using the `clear` method:

`let set = new Set; set.add(1); set.add(2); set.add(3); set.clear();`

## Practical tasks

Create a `Set` collection with initial values `1`, `2` and `3`. Display the number of elements in the collection.

Create a `Set` collection with initial values `1`, `2` and `3`. Check if the collection has an element with the value `3` and then an element with value `4`.

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