Postman - dynamic variable for a value from array

Question

How could I add an automatic environmental variable in Postman based on a value which is appearing in the endpoint response in the array?

In the example below, I would like to use the "id3" value and save it as a dynamic variable.

    {
    "test": 123,
    "test2": [],
    "test3": [
            {
                "id": 0,
                "id2": 4554336,
                "id3": 30,
                "id4": 0
            }
        ]
    }

I thought it will be simple as:

let jsonData = pm.response.json();
pm.environment.set("test_name", jsonData.test3.id);

but this set up is saving the variable with a null value.

Answer 1

 let jsonData = pm.response.json(); 
pm.environment.set("test_name", jsonData.test3[0].id3);

test3 is an array so you have to get the first object and then id3