@browser-echo/core

Core client-side functionality for streaming browser console logs to your dev terminal.

This package provides the initBrowserEcho function that patches console.* methods and forwards logs to a development server endpoint. It's designed to be used as a dependency by framework-specific providers.

Table of Contents

• Installation
• Usage
• Install MCP Server

Features

• Drop-in client patch that wraps console.log/info/warn/error/debug
• Batched HTTP requests (uses sendBeacon when available)
• Source hints (file:line:col) + stack traces
• Configurable log levels and batching
• Circular reference handling in logged objects
• No production impact (meant for development only)
• Optional network capture (opt-in): fetch, XMLHttpRequest, WebSocket

Installation

npm install -D @browser-echo/core
# or
pnpm add -D @browser-echo/core

Usage

import { initBrowserEcho } from '@browser-echo/core';

// Initialize with default options
initBrowserEcho();

// Or customize the behavior
initBrowserEcho({
  route: '/__client-logs',
  include: ['warn', 'error'],
  preserveConsole: true,
  tag: '[browser]',
  batch: { size: 20, interval: 300 },
  stackMode: 'condensed',
  // Opt-in network logging
  networkLogs: {
    enabled: true,
    captureFull: false,
    bodies: {
      request: true,
      response: true,
      maxBytes: 2048,
      allowContentTypes: ['application/json', 'text/', 'application/x-www-form-urlencoded'],
      prettyJson: true
    }
  }
});

Options

Most providers accept these options (names may appear as plugin options or component props):

type BrowserLogLevel = 'log' | 'info' | 'warn' | 'error' | 'debug';

interface BrowserEchoOptions {
  enabled?: boolean;                 // default: true (dev only)
  route?: `/${string}`;              // default: '/api/client-logs' (Next), '/__client-logs' (others)
  include?: BrowserLogLevel[];       // default: ['log','info','warn','error','debug']
  preserveConsole?: boolean;         // default: true (also keep logging in the browser)
  tag?: string;                      // default: '[browser]'
  // stacks
  stackMode?: 'none' | 'condensed' | 'full'; // default: 'full' (provider-specific; Vite supports all)
  showSource?: boolean;              // default: true (when available)
  // batching
  batch?: { size?: number; interval?: number }; // default: 20 / 300ms
  // server-side
  truncate?: number;                 // default: 10_000 chars (Vite)
  fileLog?: { enabled?: boolean; dir?: string }; // Vite-only
  // network capture (opt-in)
  networkLogs?: {
    enabled?: boolean;
    captureFull?: boolean;
    bodies?: {
      request?: boolean;
      response?: boolean;
      maxBytes?: number;                       // default 2048 bytes
      allowContentTypes?: string[];            // default ['application/json','text/','application/x-www-form-urlencoded']
      prettyJson?: boolean;                    // default true
    };
  }; // default disabled
}

Note: File logging and truncate are currently implemented in the Vite plugin's dev server middleware. Nuxt/Next providers print to stdout by default (you can extend them if you need file output there).

Framework Providers

This core package is typically used through framework-specific providers:

• @browser-echo/vite - For Vite-based projects (React, Vue, TanStack Start)
• @browser-echo/next - For Next.js App Router
• @browser-echo/nuxt - For Nuxt 3/4
• @browser-echo/react - For React (non-Vite)
• @browser-echo/vue - For Vue (non-Vite)

See the main repository for complete setup guides.

Install MCP Server

For core usage, MCP forwarding depends on your server-side route implementation. The core package only handles browser-side log collection.

📖 First, set up the MCP server for your AI assistant, then configure framework options below.

Environment Variables

• BROWSER_ECHO_MCP_URL=http://127.0.0.1:5179/mcp — Set in your server environment
• BROWSER_ECHO_SUPPRESS_TERMINAL=1 — Control terminal output in your route handler

Server Route MCP Integration

See the React MCP Settings for an example server route with MCP forwarding.

Author

Kevin Kern

License

MIT

Links

• Main Repository
• Documentation