JavaScript – How do I access a value in an array, containing an object that contains and array of objects?? I need a property of one of the objects [duplicate]

I’m new to JS and am trying to get a value from inside of this array.

assetList = 

[ 
    {data: 
        [{track: 1, status: 'ready', id: 1111111}, {track: 2, status: 'idle', id: 2222222}]
    }
];

In the console I enter:

assetList[0].data[0].id 

and I get back the value 1111111 as I expect to, however when I try to pass the value into a variable in my actual JS script as per below:

var assetListData = assetList[0].data[0].id;

I get an error back, Uncaught TypeError: Cannot read properties of undefined (reading ‘data’)

What am I doing wrong here? Thanks for your help!