Does typescript allow calling keys of interface dynamically

I have a interface :

interface MyInterface {
   field_1 : string
   field_2 : string
   // ... other fields with a certain number
}

And I have a getter function that receives an instance of MyInterface and should retrieve a value of an attribute of this object dynamically

const myFactory = (myInstance:MyInterface):string => { 
    // Here some logic to retrieve a specific number 
    // for convenience lets say that the output of this logic is 1
    let output = 1
    return myInstance[`field_${output}`] // <=== This does not work since it calls a property of the interface dynmically
}

How can I call a property of an interface dynamically ?

I saw the keyof operator :
but I am not sure how to use it here

>Solution :

You can try:

 const fieldKey = `field_${output}` as keyof MyInterface
 return myInstance[fieldKey]