Example JS to verify an app store receipt

verify-receipt.js

async verifyReceipt(encodedReceipt) {
  const body = JSON.stringify({
    'receipt-data': encodedReceipt,
    
    // Set in App Store Connect
    password: process.env.APP_STORE_SECRET,
    
    // This means Apple only returns the latest receipt info instead of all transactions.
    'exclude-old-transactions': true,
  })

  // Try to verify the receipt as if it's a real production receipt
  const productionResponse = await fetch('https://buy.itunes.apple.com/verifyReceipt', {
    method: 'POST',
    body,
  })
  
  // If it fails with status 21007 it means it's a Sandbox receipt 
  if (productionResponse.body.status === 21007) {
    const sandboxResponse = await fetch('https://sandbox.itunes.apple.com/verifyReceipt', {
      method: 'POST',
      body,
    })
    
    return sandboxResponse.body
  }

  return productionResponse.body
}