On: Deep-copying in JavaScript

[ricardobeat]

Hence being a 'naive' implementation. You can replace that with something like `deepClone(value)` + implement copying for different types, ultimately you'll end up with code like lodash's.

[drodgers → ricardobeat]

It's not just naive though, it's wrong; it won't even give you new objects although it seems like it's meant-to:

    a = [1, {foo: "bar"}];
    b = a.slice(0);

    b[1].foo = "baz";

    console.log(a)
    > [1, {foo: "baz"}]

    console.log(b)
    > [1, {foo: "baz"}]

A naive implementation would do this:

    case '[object Array]' : clone[key] = value.map((item) => deepClone(item)); break

And would thus be slower.

[ricardobeat → drodgers]

We are in agreement here. My suggestion was to make the deepClone method also take arrays, and walk through them copying values in the for loop (significantly faster than map).

Again, I linked to a full implementation at the end; was more commenting on the lack of this particular approach, wrote this on the spot as an example.