f5792c40be
Pulled ALL skills from 15 source repositories: - anthropics/skills: 16 (docs, design, MCP, testing) - obra/superpowers: 14 (TDD, debugging, agents, planning) - coreyhaines31/marketingskills: 25 (marketing, CRO, SEO, growth) - better-auth/skills: 5 (auth patterns) - vercel-labs/agent-skills: 5 (React, design, Vercel) - antfu/skills: 16 (Vue, Vite, Vitest, pnpm, Turborepo) - Plus 13 individual skills from various repos Mosaic Stack is not limited to coding — the Orchestrator and subagents serve coding, business, design, marketing, writing, logistics, analysis, and more. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
1.7 KiB
1.7 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Minimize State Variables and Derive Values | MEDIUM | fewer re-renders, less state drift | state, derived-state, hooks, optimization |
Minimize State Variables and Derive Values
Use the fewest state variables possible. If a value can be computed from existing state or props, derive it during render instead of storing it in state. Redundant state causes unnecessary re-renders and can drift out of sync.
Incorrect (redundant state):
function Cart({ items }: { items: Item[] }) {
const [total, setTotal] = useState(0)
const [itemCount, setItemCount] = useState(0)
useEffect(() => {
setTotal(items.reduce((sum, item) => sum + item.price, 0))
setItemCount(items.length)
}, [items])
return (
<View>
<Text>{itemCount} items</Text>
<Text>Total: ${total}</Text>
</View>
)
}
Correct (derived values):
function Cart({ items }: { items: Item[] }) {
const total = items.reduce((sum, item) => sum + item.price, 0)
const itemCount = items.length
return (
<View>
<Text>{itemCount} items</Text>
<Text>Total: ${total}</Text>
</View>
)
}
Another example:
// Incorrect: storing both firstName, lastName, AND fullName
const [firstName, setFirstName] = useState('')
const [lastName, setLastName] = useState('')
const [fullName, setFullName] = useState('')
// Correct: derive fullName
const [firstName, setFirstName] = useState('')
const [lastName, setLastName] = useState('')
const fullName = `${firstName} ${lastName}`
State should be the minimal source of truth. Everything else is derived.
Reference: Choosing the State Structure