Redux & Redux Toolkit Course
Redux & Redux Toolkit
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Intermediate

Manual Updates vs Immer

Definition

Comparing the legacy way of writing immutable spread operations against the modern Immer mutating syntax to understand why RTK is the standard.

Explain Like I'm New

A side-by-side comparison. Writing manual immutable updates for nested data feels like doing advanced algebra. Immer feels like writing plain, simple JavaScript.

Real World Example

Updating a user's address. `return { ...state, user: { ...state.user, address: { ...state.user.address, city: 'NY' } } }` vs `state.user.address.city = 'NY'`.

Common Use Cases

  • •Migrating old code
  • •Interview discussions

Interactive Example

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Interview Questions

basic

  • Which approach takes more lines of code: Manual or Immer?

intermediate

  • Is there any performance penalty for using Immer instead of manual spread operators?

Flash Cards

Question

Which takes more?

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Answer

Manual updates take vastly more lines of code and are highly prone to syntax errors (missing brackets).

Question

Performance penalty?

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Answer

Technically, yes. Immer uses Proxies which take a few milliseconds of processing time. However, in 99.9% of web apps, this difference is completely unnoticeable, and the developer experience gained is absolutely worth it.