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JavaScriptSetMapData Structures

JavaScript Set and Map Methods

Master Set and Map data structures in JavaScript. From basic operations to advanced patterns.

B
Bootspring Team
Engineering
January 24, 2021
7 min read

Set and Map provide efficient data storage with unique keys. Here's how to use them.

Set Basics

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Set Operations

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Map Basics

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Map vs Object

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WeakSet and WeakMap

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Practical Patterns

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Set for Array Operations

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Map for Memoization

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Best Practices

When to Use Set: ✓ Need unique values ✓ Fast membership testing ✓ Set operations (union, intersection) ✓ Removing duplicates When to Use Map: ✓ Key-value pairs with non-string keys ✓ Need insertion order ✓ Frequent additions/deletions ✓ Need size property When to Use WeakMap/WeakSet: ✓ Object references as keys ✓ Need garbage collection ✓ Storing private data ✓ Caching computed values Performance: ✓ O(1) for add, delete, has operations ✓ Use Maps over objects for dynamic keys ✓ Consider WeakMap for large datasets ✓ Avoid JSON.stringify for complex keys

Conclusion

Set and Map provide efficient, purpose-built data structures for unique values and key-value pairs. Use Set for uniqueness and membership testing, Map for flexible key types and ordered entries. WeakSet and WeakMap enable garbage collection for object-keyed data.

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