Zod TypeScript Schema 校验 is becoming increasingly widespread in frontend development. This article dives into its core principles and best practices from real projects.

Basic Usage

Let's start with the basic implementation:

type DeepPartial<T> = T extends object ? { [P in keyof T]?: DeepPartial<T[P]> } : T

interface AppConfig {
  api: { baseUrl: string; timeout: number; retries: number }
  ui: { theme: 'light' | 'dark'; language: string; pageSize: number }
}

type PartialConfig = DeepPartial<AppConfig>

function mergeConfig(defaults: AppConfig, overrides: PartialConfig): AppConfig {
  const result = { ...defaults }
  for (const key of Object.keys(overrides) as (keyof AppConfig)[]) {
    if (overrides[key] && typeof overrides[key] === 'object') {
      result[key] = { ...defaults[key], ...overrides[key] } as any
    }
  }
  return result
}

这段代码展示了基本的使用方式。实际项目中还需要考虑错误处理和边界条件。

Advanced Usage

Building on this foundation, we can further optimize:

type UnwrapPromise<T> = T extends Promise<infer U> ? U : T

async function fetchUser(id: string) {
  const res = await fetch(`/api/users/${id}`)
  return res.json() as Promise<{ id: string; name: string; email: string }>
}

type User = UnwrapPromise<ReturnType<typeof fetchUser>>

// 类型安全的事件系统
interface EventMap {
  login: { userId: string; timestamp: number }
  logout: { userId: string }
}

class TypedEmitter<T extends Record<string, any>> {
  private handlers = new Map<keyof T, Set<Function>>()
  on<K extends keyof T>(event: K, handler: (payload: T[K]) => void) {
    if (!this.handlers.has(event)) this.handlers.set(event, new Set())
    this.handlers.get(event)!.add(handler)
  }
  emit<K extends keyof T>(event: K, payload: T[K]) {
    this.handlers.get(event)?.forEach(h => h(payload))
  }
}

This pattern is very practical in large projects and can significantly reduce maintenance costs.

Practical Cases

实际项目中的用法会更复杂一些：

type DeepPartial<T> = T extends object ? { [P in keyof T]?: DeepPartial<T[P]> } : T

interface AppConfig {
  api: { baseUrl: string; timeout: number; retries: number }
  ui: { theme: 'light' | 'dark'; language: string; pageSize: number }
}

type PartialConfig = DeepPartial<AppConfig>

function mergeConfig(defaults: AppConfig, overrides: PartialConfig): AppConfig {
  const result = { ...defaults }
  for (const key of Object.keys(overrides) as (keyof AppConfig)[]) {
    if (overrides[key] && typeof overrides[key] === 'object') {
      result[key] = { ...defaults[key], ...overrides[key] } as any
    }
  }
  return result
}

Through this approach, both the testability and scalability of the code are improved.

Performance Optimization

Here is a complete example:

type UnwrapPromise<T> = T extends Promise<infer U> ? U : T

async function fetchUser(id: string) {
  const res = await fetch(`/api/users/${id}`)
  return res.json() as Promise<{ id: string; name: string; email: string }>
}

type User = UnwrapPromise<ReturnType<typeof fetchUser>>

// 类型安全的事件系统
interface EventMap {
  login: { userId: string; timestamp: number }
  logout: { userId: string }
}

class TypedEmitter<T extends Record<string, any>> {
  private handlers = new Map<keyof T, Set<Function>>()
  on<K extends keyof T>(event: K, handler: (payload: T[K]) => void) {
    if (!this.handlers.has(event)) this.handlers.set(event, new Set())
    this.handlers.get(event)!.add(handler)
  }
  emit<K extends keyof T>(event: K, payload: T[K]) {
    this.handlers.get(event)?.forEach(h => h(payload))
  }
}

Pay attention to boundary condition handling, which is critical in production.

Summary

• Don't adopt new technology just for the sake of it
• Code examples are for reference only and need to be adjusted according to your business scenario
• Zod TypeScript Schema 校验不是银弹，需要根据项目规模和技术栈选择