---

Features

• Multi-platform: Web (H5), WeChat Mini Program, Baidu Mini Program, React Native
• Full SSE Protocol: Supports event:, data:, id: fields
• TypeScript: Complete type definitions
• Async Iterator: Modern for await...of syntax
• Lifecycle Hooks: onConnect, onComplete, onError, onHeadersReceived
• Data Preprocessing: Transform data before parsing
• Unit Testing: Vitest testing infrastructure
• Version Management: Changesets for automated versioning

Installation

npm install sse-kit
# or
pnpm add sse-kit

Quick Start

import { SSEProcessor } from 'sse-kit/lib/bundle.h5.esm';      // Web
// import { SSEProcessor } from 'sse-kit/lib/bundle.weapp.esm'; // WeChat
// import { SSEProcessor } from 'sse-kit/lib/bundle.swan.esm';  // Baidu
// import { SSEProcessor } from 'sse-kit/lib/bundle.rn.esm';    // React Native

const sse = new SSEProcessor({
    url: 'https://api.example.com/sse',
    method: 'POST',
    reqParams: { query: 'hello' }
});

// Method 1: Get all events (recommended for v2.0+)
for await (const event of sse.events()) {
    console.log(event.event, event.data, event.id);
}

// Method 2: Get message events only (backward compatible)
for await (const data of sse.message()) {
    console.log(data);
}

API Reference

Constructor Options

interface ConstructorArgsType<TBody> {
    url: `https://${string}` | `http://${string}`;  // Required
    method: 'POST' | 'GET';                          // Required
    headers?: Record<string, string>;                // Request headers
    reqParams?: Record<string, string>;              // Request parameters
    timeout?: number;                                // Connection timeout (default: 60000ms)
    credentials?: 'include' | 'same-origin' | 'omit';
    enableConsole?: boolean;                         // Enable debug logs

    // Lifecycle callbacks
    onConnect?: () => void;                          // Connection established
    onComplete?: (response: unknown) => void;        // Request completed
    onError?: (err: Error) => void;                  // Error occurred
    onHeadersReceived?: (headers: HeadersType) => void;

    // Data preprocessing (called before JSON.parse)
    preprocessDataCallback?: (data: string) => string;
}

Instance Methods

Method	Return Type	Description
connect()	this	Establish connection (chainable)
events()	AsyncIterableIterator<SSEEvent<TBody>>	Get all events with event type
message()	AsyncIterableIterator<TBody>	Get message events only
close()	void	Close connection
getCurrentEventId()	number	Get current event count

Full Example

const sse = new SSEProcessor<MyDataType>({
    url: 'https://api.example.com/sse',
    method: 'POST',
    headers: { 'Authorization': 'Bearer token' },
    reqParams: { userId: '123' },
    timeout: 120000,
    enableConsole: true,

    onConnect: () => console.log('Connected'),
    onComplete: () => console.log('Completed'),
    onError: (err) => console.error('Error:', err),

    // Decode base64 data (common in mini programs)
    preprocessDataCallback: (data) => {
        try {
            return atob(data);
        } catch {
            return data;
        }
    }
});

for await (const event of sse.connect().events()) {
    if (event.event === 'message') {
        handleMessage(event.data);
    } else if (event.event === 'done') {
        console.log('Stream done');
    }
}

---

v2.0 Migration Guide

Breaking Changes

preprocessDataCallback Parameter Format Changed

Before (v1.x): Received raw SSE line with data: prefix

preprocessDataCallback: (data) => {
    if (data.startsWith('data:')) {
        return `data: ${decode(data.replace(/^data:/, ''))}`;
    }
    return data;
}

After (v2.0): Receives pure data content without data: prefix

preprocessDataCallback: (data) => {
    return decode(data);  // e.g., Base64.decode(data)
}

New Features in v2.0

• Full SSE Protocol: Supports event:, data:, id: fields
• connect() Method: Explicitly establish connection
• events() Method: Get all events with event type
• React Native Support: New platform via react-native-sse

---

Platform Notes

Platform	Import Path	Notes
Web (H5)	sse-kit/lib/bundle.h5.esm	Standard fetch-based
WeChat Mini Program	sse-kit/lib/bundle.weapp.esm	Auto UTF-8 handling
Baidu Mini Program	sse-kit/lib/bundle.swan.esm	Recommend base64 encoding
React Native	sse-kit/lib/bundle.rn.esm	Requires react-native-sse

---

Development

# Install dependencies
pnpm install

# Development (choose one)
pnpm dev:h5     # Web
pnpm dev:weapp  # WeChat Mini Program
pnpm dev:swan   # Baidu Mini Program

# Build SDK
pnpm build:sdk

# Run tests
pnpm test

# Run tests with coverage
pnpm test:coverage

# Start test server
pnpm dev:server

Project Structure

sse-kit/
├── packages/
│   ├── sse-kit/           # Main SSE client library
│   │   ├── src/
│   │   │   ├── models/    # SSEProcessor class
│   │   │   └── utils/     # Utilities and platform implementations
│   │   └── lib/           # Build output
│   ├── local-service/     # NestJS test server
│   └── taro-demo/         # Taro demo application
├── .changeset/            # Changesets configuration
└── turbo.json             # Turbo build configuration

Version Management

Using Changesets for version management:

# Create a changeset
pnpm changeset

# Apply changesets and update versions
pnpm run version

# Build and publish to npm
pnpm release

Testing

Using Vitest for unit testing:

# Run all tests
pnpm test

# Run sse-kit tests only
pnpm test:sdk

# Run with coverage
pnpm test:coverage

---

License

MIT