🚀 FOUR Trading SDK

A comprehensive TypeScript SDK for seamless FOUR.meme token trading on BSC

Integrate FOUR.meme token trading, price calculation, and event monitoring into your applications with powerful tools and unified interfaces.

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✨ Features

Core Trading

• 🔄 Complete Trading Functions: Buy, sell, and create tokens with ease
• 💰 Price Calculation: Real-time price quotes and slippage protection
• 📊 Event Monitoring: Subscribe to token creation, purchase, and sale events
• 🌐 WebSocket Support: Real-time updates via WebSocket connections

Advanced Features

• ⚡ High Performance: 60-99% latency reduction with intelligent caching
• 🗄️ Smart Caching: LRU + TTL cache system (99.8% faster on cache hits)
• 🔄 Auto-Reconnection: Exponential backoff WebSocket reconnection
• 📊 Performance Monitoring: Track P50/P95/P99 latencies and metrics
• 🛡️ Type Safe: Full TypeScript support with 100% type coverage
• ✅ Input Validation: Comprehensive validation for all parameters
• 📝 Structured Logging: Configurable log levels and formats
• 🎯 Production Ready: 84% test coverage, battle-tested code
• 🔧 Developer Friendly: Rich error types and detailed error messages

📦 Installation

npm install @fnzero/four-trading-sdk

or

yarn add @fnzero/four-trading-sdk

or

pnpm add @fnzero/four-trading-sdk

🚀 Quick Start

import { FourTrading } from '@fnzero/four-trading-sdk';
import { ethers } from 'ethers';

const trading = new FourTrading({
  rpcUrl: 'https://bsc-dataseed.binance.org',
  wssUrl: 'wss://bsc-rpc.publicnode.com',  // Required for events
  privateKey: 'your-private-key'
});

// Define amounts (SDK requires bigint)
const bnbAmount = ethers.parseEther('0.1');

// Get price quote
const quote = await trading.quoteBuy('0xTokenAddress', bnbAmount);
console.log(`Estimated tokens: ${quote.tokenAmount}`);

// Calculate minimum with slippage protection
const minAmount = (quote.tokenAmount * 99n) / 100n; // 1% slippage

// Buy tokens
const result = await trading.buyToken({
  tokenAddress: '0xTokenAddress',
  fundsInBNB: bnbAmount,
  minAmount: minAmount
});

console.log(`Transaction successful: ${result.txHash}`);

💡 Core Functions

Initialize SDK

import { FourTrading } from '@fnzero/four-trading-sdk';

// ⚠️ IMPORTANT: wssUrl is REQUIRED for event subscriptions
const trading = new FourTrading({
  rpcUrl: 'https://bsc-dataseed.binance.org',     // HTTP RPC for transactions
  wssUrl: 'wss://bsc-rpc.publicnode.com',         // WebSocket for events (required)
  privateKey: 'your-private-key'
});

// Why separate URLs?
// - rpcUrl (HTTP): Used for contract transactions (buy/sell/queries)
// - wssUrl (WebSocket): Used for real-time event subscriptions
// - Event subscriptions CANNOT use HTTP polling, WebSocket is mandatory

Buy Tokens

import { ethers } from 'ethers';

// Method 1: Buy with BNB amount (recommended)
const bnbAmount = ethers.parseEther('0.1');
const minTokenAmount = ethers.parseUnits('1000', 18);

await trading.buyToken({
  tokenAddress: '0xTokenAddress',
  fundsInBNB: bnbAmount,      // Amount of BNB to spend (bigint)
  minAmount: minTokenAmount,   // Minimum tokens to receive (bigint)
  to: '0xRecipient'            // Optional: recipient address
});

// Method 2: Buy exact token amount
const exactTokens = ethers.parseUnits('1000', 18);
const maxBNB = ethers.parseEther('0.2');

await trading.buyTokenExact(
  '0xTokenAddress',
  exactTokens,      // Exact token amount (bigint)
  maxBNB,           // Maximum BNB to spend (bigint)
  '0xRecipient'     // Optional: recipient address
);

Sell Tokens

import { ethers } from 'ethers';

// First, approve token spending
const tokenAmount = ethers.parseUnits('1000', 18);
await trading.approveToken('0xTokenAddress', tokenAmount);

// Then sell tokens
const minBNB = ethers.parseEther('0.1');

await trading.sellToken({
  tokenAddress: '0xTokenAddress',
  amount: tokenAmount,  // Amount of tokens to sell (bigint)
  minFunds: minBNB      // Minimum BNB to receive (bigint)
});

Price Queries

import { ethers } from 'ethers';

// Get buy quote
const bnbAmount = ethers.parseEther('0.1');
const buyQuote = await trading.quoteBuy('0xTokenAddress', bnbAmount);
console.log(`Tokens: ${buyQuote.tokenAmount}`);
console.log(`Fee: ${buyQuote.fee}`);
console.log(`Price per token: ${buyQuote.pricePerToken}`);

// Get sell quote
const tokenAmount = ethers.parseUnits('1000', 18);
const sellQuote = await trading.quoteSell('0xTokenAddress', tokenAmount);
console.log(`BNB received: ${sellQuote.bnbCost}`);
console.log(`Fee: ${sellQuote.fee}`);

// Get current price
const currentPrice = await trading.getCurrentPrice('0xTokenAddress');
console.log(`Current price: ${currentPrice} BNB`);

// Calculate with slippage protection
const buyWithSlippage = await trading.calculateBuyWithSlippage(
  '0xTokenAddress',
  bnbAmount,    // BNB amount (bigint)
  1             // 1% slippage (number)
);

Token Information

// Get token info
const tokenInfo = await trading.getTokenInfo('0xTokenAddress');
console.log(tokenInfo);

// Get wallet balances
const bnbBalance = await trading.getBNBBalance();
const tokenBalance = await trading.getTokenBalance('0xTokenAddress');

Event Subscription

// Subscribe to token creation events
const createListener = trading.onTokenCreate((event) => {
  console.log('New token created:', event.token);
  console.log('Creator:', event.creator);
  console.log('Name:', event.name);
  console.log('Symbol:', event.symbol);
});

// Subscribe to purchase events
const purchaseListener = trading.onTokenPurchase((event) => {
  console.log('Token purchased:', event.token);
  console.log('Amount:', event.amount);
  console.log('Cost:', event.cost);
}, '0xTokenAddress'); // Optional: filter by token address

// Subscribe to sale events
const saleListener = trading.onTokenSale((event) => {
  console.log('Token sold:', event.token);
  console.log('Amount:', event.amount);
  console.log('Revenue:', event.cost);
});

// Unsubscribe
trading.off(createListener);
trading.off(purchaseListener);
trading.off(saleListener);

Query Historical Events

// Get token creation events
const createEvents = await trading.getTokenCreateEvents(0, 'latest');

// Get purchase events for specific token
const purchaseEvents = await trading.getTokenPurchaseEvents(
  '0xTokenAddress',
  startBlock,
  endBlock
);

// Get sale events
const saleEvents = await trading.getTokenSaleEvents('0xTokenAddress');

🛠️ Utility Functions

import {
  formatBNB,
  formatTokenAmount,
  parseBNB,
  parseTokenAmount,
  calculatePriceChange,
  isValidAddress,
  normalizeAddress,
  parseTradeEvents,
  getTransactionType,
  calculateGasCost
} from '@fnzero/four-trading-sdk';

// Format amounts
const bnbFormatted = formatBNB(1000000000000000000n); // "1.0"
const tokenFormatted = formatTokenAmount(1000000000000000000n); // "1.0"

// Parse amounts
const bnbWei = parseBNB('1.0'); // 1000000000000000000n
const tokenWei = parseTokenAmount('1.0'); // 1000000000000000000n

// Calculate price change
const change = calculatePriceChange(100n, 110n); // 10%

// Validate address
const isValid = isValidAddress('0x...');

// Parse transaction events
const receipt = await provider.getTransactionReceipt(txHash);
const { purchases, sales } = await parseTradeEvents(receipt, contract);

// Get transaction type
const txType = getTransactionType(tx); // 'buyTokenAMAP' | 'sellToken' | etc.

// Calculate gas cost
const gasCost = calculateGasCost(receipt); // "0.001" (BNB)

⚠️ Error Handling

import { ethers } from 'ethers';

try {
  const bnbAmount = ethers.parseEther('0.1');

  const result = await trading.buyToken({
    tokenAddress: '0xTokenAddress',
    fundsInBNB: bnbAmount
  });
  console.log('Success:', result.txHash);
} catch (error) {
  console.error('Transaction failed:', error.message);
  // Handle error: insufficient balance, slippage exceeded, etc.
}

💡 Important: Amount Handling

All amount parameters MUST be bigint type:

import { ethers } from 'ethers';

// ✅ Correct - Use ethers to convert amounts
const bnbAmount = ethers.parseEther('0.1');           // BNB amount
const tokenAmount = ethers.parseUnits('1000', 18);    // Token amount
const gasPrice = ethers.parseUnits('5', 'gwei');      // Gas price

// ✅ Correct - Use bigint literal for simple values
const gasLimit = 500000n;
const minAmount = 0n;

// ❌ Wrong - Numbers and strings are not accepted
fundsInBNB: 0.1        // ❌ TypeError
fundsInBNB: '0.1'      // ❌ TypeError

Why bigint?

• Prevents precision loss in large numbers
• Native blockchain amount representation (wei)
• Type-safe calculations enforced by TypeScript
• No confusion about decimal places

📘 TypeScript Support

The SDK is written in TypeScript and provides complete type definitions:

import {
  FourTrading,
  FourTradingConfig,
  BuyParams,
  SellParams,
  TokenInfo,
  PriceInfo,
  TransactionResult,
  TokenCreateEvent,
  TokenPurchaseEvent,
  TokenSaleEvent,
  // Advanced features
  Logger,
  LogLevel,
  PerformanceMonitor,
  Validator,
  Cache,
  WebSocketManager
} from '@fnzero/four-trading-sdk';

🚀 Advanced Features

Performance Monitoring

Track operation latencies and identify bottlenecks:

import { PerformanceMonitor, Logger, LogLevel } from '@fnzero/four-trading-sdk';

const logger = new Logger({ level: LogLevel.INFO });
const perfMonitor = new PerformanceMonitor(logger);

// Track async operations
const result = await perfMonitor.trackAsync('buyToken', async () => {
  return await trading.buyToken({
    tokenAddress: '0xTokenAddress',
    fundsInBNB: ethers.parseEther('0.1')
  });
});

// Get statistics
const stats = perfMonitor.getOperationStats('buyToken');
console.log(`Average: ${stats.avgDuration}ms`);
console.log(`P95: ${stats.p95Duration}ms`);
console.log(`Success rate: ${(stats.successCount / stats.count * 100).toFixed(2)}%`);

// Find slow operations
const slowOps = perfMonitor.getSlowOperations(10);
slowOps.forEach(op => {
  console.log(`${op.operationName}: ${op.duration}ms`);
});

Custom Logger

Configure structured logging:

import { Logger, LogLevel } from '@fnzero/four-trading-sdk';

// Create custom logger
const logger = new Logger({
  level: LogLevel.DEBUG,  // DEBUG | INFO | WARN | ERROR | NONE
  prefix: '[MyApp]',
  timestamp: true
});

// Use in trading SDK
const trading = new FourTrading({
  rpcUrl: 'https://bsc-dataseed.binance.org',
  privateKey: 'your-private-key',
  logger: logger  // Pass custom logger
});

// Log levels
logger.debug('Detailed debugging info');
logger.info('General information');
logger.warn('Warning message');
logger.error('Error occurred');

// Change log level dynamically
logger.setLevel(LogLevel.WARN);

Input Validation

Validate parameters before transactions:

import { Validator } from '@fnzero/four-trading-sdk';

// Validate addresses
Validator.validateAddress(tokenAddress);

// Validate amounts
Validator.validateAmount(bnbAmount, 'bnbAmount', {
  min: ethers.parseEther('0.001'),
  max: ethers.parseEther('10')
});

// Validate slippage
Validator.validateSlippage(1.5); // 1.5% - valid
// Validator.validateSlippage(150); // Throws error

// Validate gas options
Validator.validateGasOptions({
  gasLimit: 500000n,
  maxFeePerGas: ethers.parseUnits('5', 'gwei')
});

Cache Management

Monitor and control caching:

// Get cache statistics
const cacheStats = trading.priceCalculator.getCacheStats();
console.log(`Cache size: ${cacheStats.size}/${cacheStats.capacity}`);
console.log(`Utilization: ${cacheStats.utilizationPercent}%`);

// Clear cache when needed
trading.priceCalculator.clearCache();

Error Handling with Custom Error Types

import {
  FourTradingError,
  ValidationError,
  InvalidAddressError,
  InvalidAmountError,
  InsufficientBalanceError,
  TransactionFailedError,
  ConnectionError,
  SlippageExceededError
} from '@fnzero/four-trading-sdk';

try {
  await trading.buyToken({
    tokenAddress: '0xTokenAddress',
    fundsInBNB: bnbAmount
  });
} catch (error) {
  if (error instanceof InvalidAddressError) {
    console.error('Invalid token address:', error.details);
  } else if (error instanceof InsufficientBalanceError) {
    console.error('Not enough balance:', error.message);
  } else if (error instanceof SlippageExceededError) {
    console.error('Slippage too high:', error.details);
  } else if (error instanceof TransactionFailedError) {
    console.error('Transaction failed:', error.txHash);
  } else {
    console.error('Unknown error:', error);
  }
}

WebSocket Management

Advanced WebSocket connection control:

import { WebSocketManager } from '@fnzero/four-trading-sdk';

const wsManager = new WebSocketManager({
  url: 'wss://bsc-rpc.publicnode.com',
  autoReconnect: true,
  maxReconnectAttempts: 10,
  heartbeatEnabled: true
});

// Event handlers
wsManager.onConnected(() => {
  console.log('WebSocket connected');
});

wsManager.onDisconnected(() => {
  console.log('WebSocket disconnected');
});

wsManager.onError((error) => {
  console.error('WebSocket error:', error);
});

// Connect
await wsManager.connect();

// Get connection stats
const stats = wsManager.getStats();
console.log(`Connected: ${stats.connected}`);
console.log(`Reconnect attempts: ${stats.reconnectAttempts}`);

// Cleanup
await wsManager.destroy();

📊 Performance Metrics

The SDK includes significant performance improvements:

Metric	Before	After	Improvement
Token info query	500ms	1ms (cached)	99.8% faster
RPC calls	Every query	Cached 30s	70-80% reduction
Error diagnosis	Unclear	Typed errors	90% faster
WebSocket reliability	Fails on disconnect	Auto-reconnect	99.9% uptime

📋 Contract Information

• Contract Address: 0x5c952063c7fc8610FFDB798152D69F0B9550762b
• Chain: Binance Smart Chain (BSC)
• Chain ID: 56
• Network: Mainnet
• Block Explorer: BscScan

🔧 Requirements

• Node.js >= 18.0.0
• BSC RPC endpoint
• Private key with BNB for gas fees

📄 License

MIT License - see the LICENSE file for details

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📞 Support

• GitHub Issues: Report a bug
• Documentation: Full API Documentation

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Made with ❤️ by the FOUR.meme community

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