In javascript, is there anyway to set a value equal to a previous key that was declared during initialization? for example,

const object = {
  a: "test",
  b: a
    }
 
 console.log(object)

or

const object = {
  a: "test",
  b: object.a
    }
 
 console.log(object)

How can I achieve this result in the console?

    { a: 'test', b: 'test' }

I understand that this is redundant, so let me explain what I'm trying to achieve.

I want to be able to set a url in one value, and then add to it using a previous value. The reason for this is to clean up the code and set formulas into one object.

Example

const object = {
  base_url: "www.google.com",
  images_url: `${base_url}/images`,
  maps_url: `${base_url}/maps`
    }
 
 console.log(object)