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Complete React Native and Expo optimization guide combining Callstack profiling with Vercel code patterns. Covers FPS, TTI, bundle size, memory, lists, animations, state, UI, and React Compiler. Use for any React Native performance, debugging, or best practices task.

Use this Skill: https://skilld.dev/gh/gigs-slc/react-native-skills/react-native

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rulesrendering-no-falsy-and.md

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Never Use && with Potentially Falsy Values

Never use {value && <Component />} when value could be an empty string or 0. These are falsy but JSX-renderable—React Native will try to render them as text outside a <Text> component, causing a hard crash in production.

Incorrect (crashes if count is 0 or name is ""):

function Profile({ name, count }: { name: string; count: number }) {
  return (
    <View>
      {name && <Text>{name}</Text>}
      {count && <Text>{count} items</Text>}
    </View>
  )
}
// If name="" or count=0, renders the falsy value → crash

Correct (ternary with null):

function Profile({ name, count }: { name: string; count: number }) {
  return (
    <View>
      {name ? <Text>{name}</Text> : null}
      {count ? <Text>{count} items</Text> : null}
    </View>
  )
}

Correct (explicit boolean coercion):

function Profile({ name, count }: { name: string; count: number }) {
  return (
    <View>
      {!!name && <Text>{name}</Text>}
      {!!count && <Text>{count} items</Text>}
    </View>
  )
}

Best (early return):

function Profile({ name, count }: { name: string; count: number }) {
  if (!name) return null

  return (
    <View>
      <Text>{name}</Text>
      {count > 0 ? <Text>{count} items</Text> : null}
    </View>
  )
}

Early returns are clearest. When using conditionals inline, prefer ternary or explicit boolean checks.

Lint rule: Enable react/jsx-no-leaked-render from eslint-plugin-react to catch this automatically.

Source: SKILL.md on GitHub

2 alerts6mo4 checks · Risk HIGH
  • Gen Agent Trust Hub7mo

    The skill is a technical React Native guide that includes a high-risk remote code execution pattern for installing a performance tool.

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    Risk: MEDIUM · No issues

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Signed by skilld at 1d299ca. This ties the file your Agent reads to that commit on GitHub. It does not review the instructions.

Last checked against GitHub 2 days ago.

Dormantupdated 8 months ago
Other metadata
metadata
{
  "author": "Callstack + Vercel",
  "version": "1.0.0",
  "tags": "react-native, expo, performance, optimization, patterns"
}

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