<!--
title: Constructor over setter
domain: ai-agents
topic: API
language: Other
source: langchain-ai/langchainjs
updated: 2024-12-13
url: https://awesomereviewers.com/reviewers/langchainjs-constructor-over-setter/
-->

Prefer passing configuration through constructor parameters rather than setting properties after instantiation. This makes APIs more predictable, enables immutability, and clearly communicates required dependencies at creation time. Additionally, use consistent method naming conventions like `.invoke()` for primary API methods.

**Instead of this:**
```javascript
const loader = new GoogleDriveLoader();
loader.recursive = true;
loader.folderId = "YourGoogleDriveFolderId";
```

**Do this:**
```javascript
const loader = new GoogleDriveLoader({
  recursive: true,
  folderId: "YourGoogleDriveFolderId"
});
```

Similarly, when adding methods to an API class, prefer descriptive action names like `invoke()` over generic terms like `call()`. This creates a more intuitive API that follows established patterns across the ecosystem.