JavaScript Interview Questions
  • JavaScript Interview Questions
  • Contact
  • Introduction
  • Question 1
  • Question 2
  • Question 3
  • Question 4
  • Question 5
  • Question 6
  • Question 7
  • Question 8
  • Question 9
  • Question 10
  • Question 11
  • Question 12
  • Question 13
  • Question 14
  • Question 15
  • Question 16
  • Question 17
  • Question 18
  • Question 19
  • Question 20
  • Question 21
  • Question 22
  • Question 23
  • Question 24
  • Question 25
  • Question 26
  • Question 27
  • Question 28
  • Question 29
  • Question 30
  • Question 31
  • Question 32
  • Question 33
  • Question 34
  • Question 35
  • Question 36
  • Question 37
  • Question 38
  • Question 39
  • Question 40
  • Question 41
  • Question 42
  • Question 43
  • Question 44
  • Question 45
  • Question 46
  • Question 47
  • Question 48
  • Question 49
  • Question 50
  • Question 51
  • Question 52
  • Question 53
  • Question 54
  • Question 55
  • Question 56
  • Question 57
  • Question 58
  • Question 59
  • Question 60
  • Question 61
  • Question 62
  • Question 63
  • Question 64
  • Question 65
  • Question 66
  • Question 67
  • Question 68
  • Question 69
  • Question 70
  • Question 71
  • Question 72
  • Question 73
  • Question 74
  • Question 75
  • Question 76
  • Question 77
  • Question 78
  • Question 79
  • Question 80
  • Question 81
  • Question 82
  • Question 83
  • Question 84
  • Question 85
  • Question 86
  • Question 87
  • Question 88
  • Question 89
  • Question 90
  • Question 91
  • Question 92
  • Question 93
  • Question 94
  • Question 95
  • Question 96
  • Question 97
  • Question 98
  • Question 99
  • Question 100
  • Epilogue
Powered by GitBook
On this page
  • Question
  • Answer

Question 54

Question

What is the difference between WeakMap and regular map for caching objects?

Answer

Here's a breakdown of the key differences between WeakMap and regular maps when it comes to object caching:

Regular Map:

  • Key Types: Can store any data type as keys (numbers, strings, objects, etc.).

  • Reference Strength: Stores keys with strong references. This means that if you cache an object in a Map, the object itself will remain in memory even if it's no longer directly referenced elsewhere in your code.

WeakMap:

  • Key Types: Can only store objects as keys. Primitive types (like numbers, strings) cannot be used.

  • Reference Strength: Stores keys with weak references. This means that if an object is cached in a WeakMap, and it's no longer referenced anywhere else in your code, the WeakMap entry will automatically be cleaned up when the garbage collector runs.

Caching Scenario: Where Things Get Interesting

Let's imagine you have a web application that fetches data from an API and stores frequently accessed results in a cache for performance improvements:

  • Regular Map: If your cached objects are relatively small, or if you need to ensure they remain accessible even if not directly used for a while, a regular Map might be suitable. However, it can lead to memory leaks if the cached data becomes large and unused.

  • WeakMap: For situations where you want to create a cache that automatically cleans up unused objects to prevent memory leaks, WeakMap is the superior choice.

In Essence:

Feature

Regular Map

WeakMap

Key Types

Any

Objects Only

Reference Strength

Strong

Weak

Memory Management

Potential for Leaks

Automatic Cleanup

When to Choose What:

  • Regular Map: When you need strong references and precise control over object lifetimes in your cache.

  • WeakMap: When automatic memory management is crucial, and you want the cache to safely release unused objects without explicit cleanup.

PreviousQuestion 53NextQuestion 55

Last updated 6 months ago