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Rule priority, scope & exceptions
Use this to align rules with the senior-level structure (P0/P1/P2, scope, exceptions/tradeoffs).
frontend ruleP1universalStack: React
reactimmutabilityarraysstate
Copy an array before sorting to avoid mutating shared state
Array.sort mutates in place; clone the array first (e.g. [...arr]) when the source could be a prop or state, since mutating state directly is unsafe.
PR: vinify-frontend · org-mining-hist-2026-06Created: Jun 19, 2026
Bad example
Old codetypescript
| 1 | const sorted = location.vintages.sort((a, b) => a.year - b.year).slice(0, 2); |
Explanation (EN)
sort changes the caller-owned array order before returning the same array.
Objašnjenje (HR)
Good example
New codetypescript
| 1 | const sorted = [...location.vintages].sort((a, b) => a.year - b.year).slice(0, 2); |
Explanation (EN)
Objašnjenje (HR)
Notes (EN)
Avoid mutating arrays owned by props, state or shared consumers; use a shallow copy or supported toSorted for a new ordered container.
Exceptions / Tradeoffs (EN)
In-place sorting is valid when the caller owns a mutable array and no other consumer needs its previous order. A shallow copy still shares element objects.