Copying Function.prototype

[ehmicky]

Behavior is different depending on whether the function to mimic is an arrow function or not:

const from = function() {}
const to = function() {}
console.log(from.prototype === to.prototype) // false
mimicFn(from, to)
console.log(from.prototype === to.prototype) // true

const from = function() {}
const to = () => {}
console.log(from.prototype === to.prototype) // false
mimicFn(from, to)
console.log(from.prototype === to.prototype) // false

This is because Function.prototype is not defined for arrow functions. mimic-fn only iterates over properties that are defined.

This leaves two questions:

• when from.prototype is not defined, should to.prototype be deleted?
• when any property is defined in to but not from, should it be deleted from to?

[sindresorhus]

when from.prototype is not defined, should to.prototype be deleted?

Yes

when any property is defined in to but not from, should it be deleted from to?

Yes, but it should be clearly documented.

[ehmicky]

I will submit a PR for this after #18 is merged (to avoid conflicts).

[ehmicky]

PR at #28