object.assign does not copy functions [duplicate]

Question

I have a common typescript class with some functions.

When I do this.selected = Object.assign({} as AssignedTestType, newTestType);

the selected instance does not own that functions which are in the type AssignedTestType.

How can I make a 'deep' copy with object.assign? or any alternative method?

Answer 1

object.assign does not copy functions

That's untrue

let x = {a: y => y * 2}
let z = Object.assign({}, x)
console.log(z.a(5)); // 10

the selected instance does not own that functions which are in the type AssignedTestType.

Now this part is true. Object.assign will only do a shallow copy and will only enumerate own props

Answer 2

If the properties you're looking to copy are in the prototype of newTestType, they will not be copied, since Object.assign only copies an object instance's own properties.

The alternatives are to either instantiate whatever constructor you used to create newTestType, and assign the resulting instance to this.selected, or to create an empty object and set its prototype to newTestType. In either case, Object.assign is the wrong tool to use here.