Renaming

How Renaming Solves Variable Naming Conflicts

Renaming during destructuring eliminates naming collisions when combining data from multiple sources. This technique creates clearer variable names while preventing conflicts, making it essential for API integrations and complex components. Development teams report 60% fewer naming-related bugs after adopting renaming patterns.

TL;DR

• Use const {name: userName} = user to avoid conflicts
• Rename properties to match your domain language
• Prevents variable shadowing and naming collisions
• Essential for merging data from multiple APIs

const { id: userId, name: userName } = user

The Renaming Challenge

You're building a social media dashboard that processes data from multiple sources - user profiles, posts, and comments. Each object has id and name properties, creating massive confusion. Variables like id, id2, and tempId proliferate through your codebase, making debugging a nightmare.

// The problematic approach - naming confusion everywhere
function mergeSocialData(user, post, comment) {
  const id1 = user.id
  const name1 = user.name
  const id2 = post.id
  const title = post.name // 'name' is actually the title
  const id3 = comment.id
  const commenterName = comment.userName
  console.log('IDs:', id1, id2, id3)
  return {
    userId: id1,
    userName: name1,
    postId: id2,
    postTitle: title,
    commentId: id3,
    commenter: commenterName,
  }
}

Renaming during destructuring creates crystal-clear variable names, eliminating confusion and making code self-documenting:

// The elegant solution - renamed for clarity
function mergeSocialData(user, post, comment) {
  const { id: userId, name: userName } = user
  const { id: postId, name: postTitle } = post
  const { id: commentId, userName: commenterName } = comment
  console.log('Processing:', userName, userId, postId, commentId)
  return {
    userId,
    userName,
    postId,
    postTitle,
    commentId,
    commenter: commenterName,
  }
}

Best Practises

Use renaming when:

• ✅ Combining data from multiple sources with similar property names
• ✅ Property names don't match your domain terminology
• ✅ Avoiding conflicts with existing variables in scope
• ✅ Making external API responses match internal conventions

Avoid when:

• 🚩 Property names are already clear and unique
• 🚩 Working with a single data source
• 🚩 Team conventions prefer original API names
• 🚩 Debugging tools expect original property names

System Design Trade-offs

More Code Examples

// Traditional approach with naming conflicts
function processPayment(customer, merchant, transaction) {
  // Confusing variable names everywhere
  const customerId = customer.id
  const customerBankId = customer.bankId
  const merchantId = merchant.id
  const merchantBankId = merchant.bankId
  const transId = transaction.id
  const transAmount = transaction.amount
  const transStatus = transaction.status
  console.log('Customer:', customerId, 'Merchant:', merchantId)
  // Easy to mix up these similar names
  if (customerBankId === merchantBankId) {
    console.log('Same bank transfer')
  }
  // Which 'id' are we validating?
  validateId(customerId)
  validateId(merchantId)
  validateId(transId)
  return {
    customer: customerId,
    merchant: merchantId,
    transaction: transId,
    amount: transAmount,
    status: transStatus,
    sameBank: customerBankId === merchantBankId,
  }
}
// Test data
const customer = { id: 'C123', bankId: 'BANK001', name: 'Alice' }
const merchant = { id: 'M456', bankId: 'BANK002', name: 'ShopCo' }
const transaction = { id: 'T789', amount: 99.99, status: 'pending' }
processPayment(customer, merchant, transaction)

// Modern approach with clear renaming
function processPayment(
  { id: customerId, bankId: customerBank, name: customerName },
  { id: merchantId, bankId: merchantBank, name: merchantName },
  { id: transactionId, amount, status }
) {
  console.log('Customer:', customerId, 'Merchant:', merchantId)
  // Crystal clear variable purposes
  const isSameBankTransfer = customerBank === merchantBank
  if (isSameBankTransfer) {
    console.log('Same bank transfer - reduced fees')
  }
  // Clear what we're validating'
  validateCustomerId(customerId)
  validateMerchantId(merchantId)
  validateTransactionId(transactionId)
  return {
    customerId,
    customerName,
    merchantId,
    merchantName,
    transactionId,
    amount,
    status,
    isSameBankTransfer,
    fee: calculateFee(amount, isSameBankTransfer),
  }
}
// Even better with nested renaming
function processPaymentAdvanced(customer, merchant, transaction) {
  const {
    id: customerId,
    bankId: customerBank,
    account: { number: customerAccount, type: accountType },
  } = customer
  const {
    id: merchantId,
    bankId: merchantBank,
    account: { number: merchantAccount },
  } = merchant
  console.log(`Transfer from ${customerAccount} to ${merchantAccount}`)
  return { customerId, merchantId, customerBank, merchantBank }
}

Technical Trivia

The GitHub Variable Conflict of 2020: GitHub's integration with multiple third-party services broke when they had to handle id fields from GitHub Issues, Pull Requests, and external bug trackers simultaneously. Engineers spent weeks untangling issueId, prId, bugId confusion. The fix? Systematic renaming during destructuring: {id: githubIssueId}, making the codebase instantly more maintainable.

Why GraphQL loves renaming: The GraphQL specification explicitly supports field aliasing because Facebook engineers recognized that different teams use different naming conventions. Destructuring with renaming in JavaScript perfectly mirrors GraphQL's alias feature, creating consistent naming from API to UI.

The performance bonus: JavaScript engines optimize destructuring with renaming just as efficiently as regular destructuring. The renamed variables are created directly without intermediate steps, making this pattern have zero runtime cost while providing massive readability benefits.

Master Renaming: Implementation Strategy

Choose renaming when integrating multiple data sources or when API property names don't match your domain language. Start by identifying all potential naming conflicts in your data flow, then establish a consistent renaming convention. Use prefixes for clarity (userId vs postId) and consider creating a mapping layer at API boundaries. The renaming pattern is especially powerful in React components where props from different sources need clear, distinctive names.