HouYunFei
fb79a15508
- 添加 sections 定义文件，包含性能优化各领域分类 - 添加规则模板文件，规范文档结构和标签定义 - 添加异步操作优化规则，包括防止瀑布流、并行化、延迟等待等 - 添加包大小优化规则，包括避免桶式导入、动态导入、预加载等 - 添加服务端性能优化规则，包括 API 路
837 B
837 B
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Build Index Maps for Repeated Lookups | LOW-MEDIUM | 1M ops to 2K ops | javascript, map, indexing, optimization, performance |
Build Index Maps for Repeated Lookups
Multiple .find() calls by the same key should use a Map.
Incorrect (O(n) per lookup):
function processOrders(orders: Order[], users: User[]) {
return orders.map(order => ({
...order,
user: users.find(u => u.id === order.userId)
}))
}
Correct (O(1) per lookup):
function processOrders(orders: Order[], users: User[]) {
const userById = new Map(users.map(u => [u.id, u]))
return orders.map(order => ({
...order,
user: userById.get(order.userId)
}))
}
Build map once (O(n)), then all lookups are O(1). For 1000 orders × 1000 users: 1M ops → 2K ops.