How to read a dataLayer?

Good afternoon guys,

I need to bring a dataLayer to my system. The people working with Google Tag Manager have created some dataLayer and I need to get some information with the javascript to use in other places.

How can I read a certain dataLayer and get its information? DataLayer example:

dataLayer.push({
        'transactionId': '{{mov_vehicle_lead}}',
        'transactionTotal': '{{PProd_Price_AmericanStandard}}',
        'transactionProducts': [{
            'sku': '{{PProd - VehicleID}}',
            'name': '{{PProd_Veiculo}}',
            'category': '{{PProd_Marca}}',
            'price': '{{PProd_Price_AmericanStandard}}',
            'quantity': '{{Quantidade}}'
    }],
    'event': 'transactionComplete'
    });

Thanks for the help! Thanks!