store values of selected checkboxes in array in google AMP

I want to have an array as state and I want to store values selected checkboxes in that state ... how can I achieve this? Also why e.target.checked is always false even if I select it ?

```

{
"animals": []
}

cat

dog

const cat = document.getElementById('cat')
cat.addEventListener('change',e=>{
console.log(e.target.checked) //this is always false ... buy why ??
})
//how to store values of selected checkboxes in checkbox.animales state ??

```

Start by reproducing the inline AMP example and observing the checkbox change event. Then inspect AMP Script event and state-handling behavior; done means the example reports the selected state correctly and stores selected values in checkbox.animals.

Written by the indexing model from the issue text.