How to access an Object’s values using arr.reduce()

I am trying to achieve the below:

var arr = [
 {name: 'width', value: 10}, 
 {name: 'height', value: 20}, 
]

arr.reduce((ack, item)=>{
  ack.width = item.value
  ack.height = item.value
  return ack
},{})

//Expected output:

{width: 10, height: 20}

//Actual output:

{width: 20, height: 20}

Maybe I don’t understand how .reduce() works a 100%?

Thanks in advance for your help