mirror of
https://github.com/kjanat/livedash-node.git
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Kaj Kowalski
cd05fc8648
- Fix syntax errors in skills markdown files (.github/skills, .opencode/skills) - Change typescript to tsx for code blocks with JSX - Replace ellipsis (...) in array examples with valid syntax - Separate CSS from TypeScript into distinct code blocks - Convert JavaScript object examples to valid JSON in docs - Fix enum definitions with proper comma separation
25 lines
530 B
Markdown
25 lines
530 B
Markdown
---
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title: Use Set/Map for O(1) Lookups
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impact: LOW-MEDIUM
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impactDescription: O(n) to O(1)
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tags: javascript, set, map, data-structures, performance
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---
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## Use Set/Map for O(1) Lookups
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Convert arrays to Set/Map for repeated membership checks.
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**Incorrect (O(n) per check):**
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```typescript
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const allowedIds = ["a", "b", "c"];
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items.filter((item) => allowedIds.includes(item.id));
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```
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**Correct (O(1) per check):**
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```typescript
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const allowedIds = new Set(["a", "b", "c"]);
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items.filter((item) => allowedIds.has(item.id));
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```
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