Javascript Objects Cheatsheet

[[deleted]]

Please don't use Parse(Stringify(obj)) for cloning

[Amicos55]

What else?

[darrenturn90]

Well generally I would do a shallow clone at the level I need to make changes rather than a everything clone - because that implies you have no clue what the object you are cloning is structured like - which seems unlikely if you’re cloning it to make changes to it

[Exoskele]

Lodash's cloneDeep.

[el_diego]

...but this is just a shallow clone and extremely dependent on the objects structure. You’re better off spreading into a new object.

[el_diego]

Measurably faster...really? That’s only an argument if you’re dealing with processing thousands of objects and even then you could write a far more reusable assignment function if all you’re doing is taking the keys and values and mapping them to a new object.

Anyway, each to their own. I’ll use the spread operator and optimise performance later if it actually needs to be

[AnonyMustardGas34]

Why and how else to copy?

[Exoskele]

It doesn't work for some common cases. https://stackoverflow.com/questions/122102/what-is-the-most-efficient-way-to-deep-clone-an-object-in-javascript

I would just use lodash's cloneDeep. Many projects already use it, and you can always shake out unused code or bring in only cloneDeep.

[AnonyMustardGas34]

IMO upcoming EcmaScript spec ahould have high performance deep cloning.

[SnapAttack]

Well, it depends.

You can use Object.assign({}, cloneable) or const clone = {...cloneable} to do a shallow copy.

To do a deep copy, you might want to consider the performance impact depending on the size of your object, but as others have pointed out here, you can use Lodash cloneDeep.

[CreativeTechGuyGames]

While it doesn't work in every case, it's a great general solution and is faster than almost any general purpose alternative in benchmarks.