停止在混乱中搜索
.

宽事件和结构化错误，用于 TypeScript。每条请求一个日志，完整上下文，解释原因和修复方法的错误。

Fix your logs GitHub

前端Nuxt / Next.js

API 服务Nitro / Express

request logs

live

▍

Workers后台任务

数据库查询与事件

? 哪里失败了？

? 为什么？

? 哪些用户？

? 如何修复？

简单的 API

设置上下文。
获取答案.

使用 log.set 累积上下文，使用 why 抛出结构化错误和修复方法。一个宽事件捕获一切，无论请求成功或失败。

Wide events Root cause Fix suggestion

快速入门指南

checkout.post.ts

export default defineEventHandler(async (event) => {
  const log = useLogger(event)

  log.set({ user: { id: user.id, plan: user.plan } })
  log.set({ cart: { items: 3, total: 9999 } })

  if (!charge.success) {
    throw createError({
      status: 402,
      why: 'Card declined by issuer',
      fix: 'Try a different card',
    })
  }

  return { orderId: charge.id }
})

output

INFOPOST/api/checkout(234ms)

user: { id: 1842, plan: "pro" }

cart: { items: 3, total: 9999 }

status: 200

requestId: "req_8f2k..."

✓ One log with full context

ERRORPOST/api/checkout402

message: "Payment failed"

why: "Card declined by issuer"

fix: "Try a different card"

user: { id: 1842, plan: "pro" }

✓ Actionable error with context

代理就绪

为代理而构建.

结构化字段、可机读的上下文和可操作元数据，为 AI 代理提供诊断和解决问题所需的一切。启用文件系统排水以将 NDJSON 日志本地写入，并让代理直接读取它们。

Structured context Machine-parseable Local NDJSON files

代理技能设置

outputERROR

ERRORPOST/api/payment402

message: "Payment processing failed"

why: "Card issuer declined: insufficient funds"

fix: "Retry with a different payment method"

user: { id: 1842, plan: "pro" }

links: ["stripe.com/docs/declines"]

AI Agent analyzing

Reading structured error context...

→

Root cause

Card declined by issuer — insufficient funds

→

User impact

Pro plan user (#1842) blocked on payment

→

Suggested fix

Prompt for alternate payment method

→

Documentation

stripe.com/docs/declines/codes

✓ Auto-created issue PAY-4521

排水管道

发送到任何地方.

批量写入、自动重试和扇出到多个目标。日志通过永不阻塞响应的管道流动。

Batching Retry & backoff Fan-out

探索适配器

Non-blocking

Pipeline runs in the background. Your response ships immediately.

Guaranteed delivery

Exponential backoff with jitter ensures logs reach every destination.

Bring your own drain

Write a simple function to send logs anywhere.

evlog-drain.ts

import { createDrainPipeline } from 'evlog/pipeline'
import { createAxiomDrain } from 'evlog/axiom'
import { createSentryDrain } from 'evlog/sentry'

const pipeline = createDrainPipeline({
  drains: [
    createAxiomDrain(),
    createSentryDrain(),
  ],
  batchSize: 50,
  flushInterval: 5000,
})

evlog

BATCH · RETRY · FANOUT

Axiom

OTLP

Sentry

PostHog

Better Stack

+ File System·Custom drains·and more

客户端日志

查看完整画面.

捕获浏览器事件并将其排水到服务器。自动批量、重试和页面感知的刷新，以及与服务器相同的客户端到服务器管道。

Auto-batch sendBeacon Origin validation

客户端日志指南

Automatic batching

Events are batched by size and time interval, reducing network overhead.

Page-aware delivery

Switches to sendBeacon when the page is hidden. No event left behind.

Server-side validation

Origin check, payload sanitization, and source tagging on every ingest.

http-drain.ts

import { createHttpLogDrain } from 'evlog/http'

const drain = createHttpLogDrain({
  drain: {
    endpoint: '/api/_evlog/ingest',
  },
  pipeline: {
    batch: { size: 25, intervalMs: 2000 },
    retry: { maxAttempts: 2 },
  },
})

initLogger({ drain })

BrowserEVENTS

BATCH · FLUSH

PipelineRETRY · BACKOFF

POST · BEACON

ServerVALIDATE · DRAIN

auto-flush on page visibility change

采样

保留重要内容.

两级过滤：头部采样按级别丢弃噪声，尾部采样挽救关键事件。永远不会错过错误、慢速请求或关键路径。

Head sampling Tail sampling Per-level rates

采样指南

evlog.config.ts

initLogger({
  sampling: {
    // Head: per-level rates
    rates: {
      info:  10,   // keep 10%
      warn:  50,   // keep 50%
      error: 100,  // always
    },
    // Tail: force keep if match
    keep: [
      { status: 400 },
      { duration: 1000 },
      { path: '/api/critical/**' },
    ]
  }
})

log stream

HEADTAIL

INFOGET/api/users45ms

INFOPOST/api/orders120ms

INFOGET/api/health12ms

WARNPOST/api/payment340ms

INFOGET/api/search1240ms

ERRORPOST/api/checkout450ms

INFOGET/api/feed32ms

INFOPOST/api/critical/alert55ms

5 kept·3 dropped· noise reduced without data loss

AI 可观测性

使 AI 调用
可观测.

您的 AI 端点是黑盒。您不知道每个请求消耗多少令牌，模型调用了哪些工具，或者流的速度有多快。用一行代码包装您的模型，每个调用都将被捕获到宽事件中。成本跟踪、工具可见性、流式性能、缓存命中、推理令牌。

Token tracking Tool calls Streaming metrics

AI SDK 集成

Zero boilerplate

Wrap the model, done. No manual token tracking needed.

Works with everything

generateText, streamText, ToolLoopAgent, generateObject.

Cost and performance

Token usage, cache hits, time to first chunk, tokens per second.

wide event

const ai = createAILogger(log)

const result = streamText({
  model: ai.wrap('anthropic/claude-sonnet-4.6'),
  messages,
})

INFOPOST/api/chat(4.5s)

status: 200

requestId: "req_8f2k..."

Which model? How many tokens? What did it cost?

INFOPOST/api/chat(4.5s)

status: 200

ai.model: "claude-sonnet-4.6"

ai.inputTokens: 3312

ai.outputTokens: 814

ai.reasoningTokens: 225

ai.toolCalls: ["searchWeb", "queryDB"]

ai.steps: 3

ai.msToFirstChunk: 234

ai.tokensPerSecond: 180

性能

添加日志记录，:br 而不是开销.

零依赖，5.2 kB gzip，约每个请求 3µs。在 pino、consola 和 winston 之间进行了基准测试。在宽事件场景中比 pino 快 8 倍，同时产生更丰富、更有用的输出。

Zero-alloc hot path CodSpeed CI Open source benchmarks

基准测试结果

benchmark

evlog

1.8M

consola

1.0M1.7x slower

pino

508K3.4x slower

winston

203K8.6x slower

ops/sec · higher is better · silent mode (no I/O)

evlog

1.9M

pino

871K2.1x slower

winston

569K3.3x slower

consola

272K6.8x slower

ops/sec · higher is better · silent mode (no I/O)

evlog

20.5M

pino

7.4M2.8x slower

winston

5.4M3.8x slower

consola

299K68.6x slower

ops/sec · higher is better · silent mode (no I/O)

0deps/5.2 kBgzip/12frameworks/tree-shakeable

why it's fast

1 event, not N log lines

Accumulate context, emit once. 75% less data downstream.

In-place mutations

No object spreads, no copies. Direct recursive merge.

Lazy allocation

Timestamps, sampling context — created only when needed.

No serialization until drain

Plain objects throughout. JSON.stringify runs once at the end.

Zero dependencies

No transitive deps. Nothing to audit, nothing to break.

Total overhead per request

create + 3x set + emit + sampling + enrichers

~3µs

0.003ms

框架

您的堆栈已覆盖.

每个主流框架的本地集成。一次导入，零配置，到处相同的 API。Vite 插件添加了自动初始化、调试剥离和源位置，适用于任何基于 Vite 的堆栈。

框架集成

Vite

server/api/checkout.post.ts

export default defineEventHandler(async (event) => {
  const log = useLogger(event)
  const { cartId } = await readBody(event)

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: '支付失败',
      why: charge.decline_reason,
      fix: '尝试其他支付方式',
    })
  }

  return { orderId: charge.id }
})

app/api/checkout/route.ts

import { withEvlog, useLogger } from '@/lib/evlog'
import { createError } from 'evlog'

export const POST = withEvlog(async (req) => {
  const log = useLogger()
  const { cartId } = await req.json()

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: '支付失败',
      why: charge.decline_reason,
      fix: '尝试其他支付方式',
    })
  }

  return Response.json({ orderId: charge.id })
})

src/routes/api/checkout/+server.ts

import { json } from '@sveltejs/kit'
import { createError } from 'evlog'
import { useLogger } from 'evlog/sveltekit'
import type { RequestHandler } from './$types'

export const POST: RequestHandler = async ({ request }) => {
  const log = useLogger()
  const { cartId } = await request.json()

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: '支付失败',
      why: charge.decline_reason,
      fix: '尝试其他支付方式',
    })
  }

  return json({ orderId: charge.id })
}

routes/api/checkout.post.ts

import { defineHandler, readBody } from 'nitro/h3'
import { useLogger, createError } from 'evlog/nitro/v3'

export default defineHandler(async (event) => {
  const log = useLogger(event)
  const { cartId } = await readBody(event)

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: '支付失败',
      why: charge.decline_reason,
      fix: '尝试其他支付方式',
    })
  }

  return { orderId: charge.id }
})

src/routes/api/checkout.ts

import { createFileRoute } from '@tanstack/react-router'
import { useRequest } from 'nitro/context'
import { createError } from 'evlog'
import type { RequestLogger } from 'evlog'

export const Route = createFileRoute('/api/checkout')({
  server: {
    handlers: {
      POST: async ({ request }) => {
        const req = useRequest()
        const log = req.context.log as RequestLogger
        const { cartId } = await request.json()

        const cart = await db.findCart(cartId)
        log.set({ cart: { items: cart.items.length, total: cart.total } })

        const charge = await stripe.charge(cart.total)
        log.set({ stripe: { chargeId: charge.id } })

        if (!charge.success) {
          throw createError({
            status: 402,
            message: '支付失败',
            why: charge.decline_reason,
            fix: '尝试其他支付方式',
          })
        }

        return Response.json({ orderId: charge.id })
      },
    },
  },
})

app/routes/api.checkout.tsx

import { loggerContext } from 'evlog/react-router'
import { createError } from 'evlog'

export async function action({ request, context }: Route.ActionArgs) {
  const log = context.get(loggerContext)
  const { cartId } = await request.json()

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  if (!charge.success) {
    throw createError({
      status: 402,
      message: '支付失败',
      why: charge.decline_reason,
      fix: '尝试其他支付方式',
    })
  }

  return Response.json({ orderId: charge.id })
}

app.module.ts

import { Module } from '@nestjs/common'
import { EvlogModule } from 'evlog/nestjs'
import { createAxiomDrain } from 'evlog/axiom'

@Module({
  imports: [
    EvlogModule.forRoot({
      drain: createAxiomDrain(),
    }),
  ],
})
export class AppModule {}

src/index.ts

import { evlog, useLogger } from 'evlog/express'
import { createAxiomDrain } from 'evlog/axiom'

const app = express()
app.use(evlog({ drain: createAxiomDrain() }))

app.post('/checkout', async (req, res) => {
  const log = useLogger()
  const { cartId } = req.body

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  res.json({ orderId: charge.id })
})

src/index.ts

import { evlog, type EvlogVariables } from 'evlog/hono'
import { createAxiomDrain } from 'evlog/axiom'

const app = new Hono<EvlogVariables>()
app.use(evlog({ drain: createAxiomDrain() }))

app.post('/checkout', async (c) => {
  const log = c.get('log')
  const { cartId } = await c.req.json()

  const cart = await db.findCart(cartId)
  log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  log.set({ stripe: { chargeId: charge.id } })

  return c.json({ orderId: charge.id })
})

src/index.ts

import { evlog } from 'evlog/fastify'
import { createAxiomDrain } from 'evlog/axiom'

const app = Fastify({ logger: false })
await app.register(evlog, { drain: createAxiomDrain() })

app.post('/checkout', async (request) => {
  const { cartId } = request.body

  const cart = await db.findCart(cartId)
  request.log.set({ cart: { items: cart.items.length, total: cart.total } })

  const charge = await stripe.charge(cart.total)
  request.log.set({ stripe: { chargeId: charge.id } })

  return { orderId: charge.id }
})

src/index.ts

import { evlog } from 'evlog/elysia'
import { createAxiomDrain } from 'evlog/axiom'

const app = new Elysia()
  .use(evlog({ drain: createAxiomDrain() }))
  .post('/checkout', async ({ log, body }) => {
    const { cartId } = body

    const cart = await db.findCart(cartId)
    log.set({ cart: { items: cart.items.length, total: cart.total } })

    const charge = await stripe.charge(cart.total)
    log.set({ stripe: { chargeId: charge.id } })

    return { orderId: charge.id }
  })

src/worker.ts

import { initWorkersLogger, createWorkersLogger } from 'evlog/workers'

initWorkersLogger({ env: { service: 'checkout-worker' } })

export default {
  async fetch(request, env) {
    const log = createWorkersLogger(request)

    const { cartId } = await request.json()
    const cart = await env.DB.findCart(cartId)
    log.set({ cart: { items: cart.items.length, total: cart.total } })

    log.emit()
    return Response.json({ orderId: cart.id })
  },
}

scripts/migrate-users.ts

import { initLogger, createLogger } from 'evlog'

initLogger({ env: { service: 'migrate' } })

const log = createLogger({ task: 'user-migration' })

const users = await db.query('SELECT * FROM legacy_users')
log.set({ found: users.length })

for (const user of users) {
  await newDb.upsert({ id: user.id, email: user.email, plan: user.plan })
}

log.set({ migrated: users.length, status: 'complete' })
log.emit()

更好的日志
今晚就能交付今晚.

宽事件、结构化错误，简单易设置。在 10 分钟内设置 evlog。未来的你会感谢现在的你。

开始使用在 GitHub 查看

停止在混乱中搜索 .

设置上下文。 获取答案.

为代理而构建.

发送到任何地方.

查看完整画面.

保留重要内容.

使 AI 调用 可观测.

添加日志记录，:br 而不是开销.

您的堆栈已覆盖.

更好的日志今晚就能交付 今晚.

停止在混乱中搜索
.

设置上下文。
获取答案.

使 AI 调用
可观测.

更好的日志
今晚就能交付今晚.