JS how to get a list of elements in a collection object

1、 The collection style is shown below ：

2、 Our need is , How to get all the collections id list , Here's the picture ：

3、 Solution use map Function ,arr It's our collective data ：

arr.map(user => { return user.id }

4、 Other commonly used traversal functions are find、filter

find： You can find qualified objects in the collection

filter： You can filter out objects that meet our criteria