javascript / intermediate
Snippet
Efficient Data Extraction with flatMap
flatMap combines mapping and flattening into a single pass. It is particularly useful when you need to extract nested arrays from a list of objects and want a single, flat result list.
snippet.js
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const posts = [{ id: 1, tags: ['js', 'web'] },{ id: 2, tags: ['nextjs'] },{ id: 3, tags: ['react', 'web'] }];const allUniqueTags = [...new Set(posts.flatMap(p => p.tags))];// Result: ['js', 'web', 'nextjs', 'react']
nextjs
Breakdown
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posts.flatMap(p => p.tags)
Maps over each post and flattens the resulting arrays into one level.
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...new Set(...)
A common pattern to remove duplicate values from an array.