👀 Views: 1 💬 Answers: 1 📅 Created: 2025-06-11

javascript arrays performance JavaScript

Hey everyone, I'm running into an issue that's driving me crazy. I'm updating my dependencies and I've been banging my head against this for hours. I've been banging my head against this for hours... I'm currently working on an application using JavaScript (Node.js v14.17.0) where I need to combine several arrays of objects into one without introducing duplicates. Each object in the arrays has a unique identifier called `id`. I attempted to use the `concat` method followed by `filter`, but I’m running into performance issues when the arrays get large (e.g., thousands of entries). Here’s the code I tried: ```javascript const array1 = [ { id: 1, name: 'Alice' }, { id: 2, name: 'Bob' } ]; const array2 = [ { id: 2, name: 'Bob' }, { id: 3, name: 'Charlie' } ]; const combined = array1.concat(array2); const unique = combined.filter((value, index, self) => index === self.findIndex((t) => (t.id === value.id)) ); console.log(unique); ``` While this works for smaller arrays, it becomes noticeably slow with larger datasets, and I get performance warnings in my Node.js environment. I also noticed that `findIndex` has a time complexity of O(n), making the entire operation O(n^2). I attempted using a `Set` to track unique identifiers to optimize this process. Here’s what I tried: ```javascript const uniqueIds = new Set(); const uniqueOptimized = []; combined.forEach(item => { if (!uniqueIds.has(item.id)) { uniqueIds.add(item.id); uniqueOptimized.push(item); } }); console.log(uniqueOptimized); ``` This second approach seems to be faster, but I want to ensure that I’m not missing any edge cases when handling array combinations. Is there a more efficient way to achieve this, or any best practices for maintaining performance while combining large arrays of objects? This is part of a larger service I'm building. Is there a better approach? This is my first time working with Javascript 3.10. Is there a simpler solution I'm overlooking? I recently upgraded to Javascript 3.10. I'd love to hear your thoughts on this.