how to use interpolation to get value in a model

Question

I have data in model, I also have a variable which contains value in this model

 buildField = ['dataArray'][0]['person']['firstname'].

How I can use it with model ? I have tried interpolation

 console.log(resultat build ${_model+${buildField}});

But that does not work –

_model['dataArray'][0]['person']['firstname'] exist and gives a value