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How to clone anything in JavaScript

Published Dec 29 2022

We used to do all sorts of stuff in JavaScript land in regards to cloning.

Why?

Because ..references.

Primitive types (strings, numbers, booleans..) are always correctly “cloned” because they are passed by value.

Everything else (objects, arrays, dates, whatever) is an object. And objects are passed by reference.

So we had to do deep cloning using various ways otherwise you end up with the same object reference, under a different name.

But it’s 2023 and we can use structuredClone().

const b = structuredClone(a)

This also deeply clones non-primitive types.

Just pay attention it’s a recent API, so if you use it in the browser make sure you use a build tool that provides core-js (babel) polyfills.



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