Dynamic variable for a value from array in Postman

[Amritpal]

Any ideas on 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.

[chanisef]

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