cloneDeep() does not preserve ES5 property attributes

[mbrowne]

Consider the following example:

var o = {};
Object.defineProperty(o, 'foo', {enumerable:true, writable:false, value:'f'});
var o2 = _.clone(o);

console.log(Object.getOwnPropertyDescriptor(o2, 'foo'));

The property descriptor on the copied object specifies the property as writable even though the original property wasn't writable.

I also noticed that clone() and cloneDeep() only copy enumerable properties, but that's mentioned in the documentation so I assume it's deliberate (might be nice to add an option to copy them if desired).

[jdalton]

Hi @mbrowne!

This is by design. Preserving attribute descriptors is super expensive. It's part of the tradeoffs we make for being a general purpose util.

[mbrowne]

Thanks for the quick clarification! The docs could be clearer on this, but I just looked again and it does say that properties "are cloned as plain objects", which I'm guessing might have been meant to indicate that.

[lock]

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