# Useful features of Map collections

`Map` 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:

`console.log(map.size);`

## Checking for a key presence

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

`console.log(map.has(arr1));`

## Deletion by key

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

`map.delete(arr1);`

## Clearing a collection

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

`map.clear();`
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