Benchmark: Map vs Object (w/delete)

Script Preparation code:

var map = new Map();
var obj = {};

map.set('a', 5);
obj['b'] = 5;
delete obj['b'];
obj['a'] = 5;

var i = 0, count = 10, a;

Tests:

Map lookup
for (i = 0; i < count; i++) { a = map.get('a'); }
Obj lookup
for (i = 0; i < count; i++) { a = obj['a']; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map lookup
Obj lookup

Fastest: N/A

Slowest: N/A

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Measuring different approaches to JavaScript microbenchmarks can be helpful for software engineers who want to optimize their code or understand the performance characteristics of various libraries and techniques.

In this benchmark, we're testing two options: using a `Map` object versus an ordinary `Object`. Both data structures are used as lookups to retrieve values stored under specific keys.

**Options being compared:**

1. **Map**: A Map is an unordered collection of key-value pairs that allows you to store and look up values efficiently using the `get()` method.
2. **Object**: An object is a collection of key-value pairs, but it's not designed for efficient lookup. Instead, you use dot notation (`obj.key`) or bracket notation (`obj['key']`) to access values.

**Pros and Cons:**

* Using a Map has several advantages:
	+ Efficient lookups using `get()` method with an average time complexity of O(1), making it suitable for large datasets.
	+ Maps are mutable, meaning you can add or remove key-value pairs dynamically.
* However, using a Map also has some drawbacks:
	+ Memory usage: Maps consume more memory than objects because they store the keys and values in separate data structures.
* Using an object has its own set of pros and cons:
	+ Lightweight: Objects use less memory than Maps since they don't require additional storage for keys.
	+ Familiar syntax: Object notation is widely used and familiar to most JavaScript developers.

However, objects can be slower for lookups due to the need for string manipulation (e.g., `obj['a']`) or using `in` operator (`'a' in obj`). This is because modern JavaScript engines often use caching mechanisms that don't work as well with bracket notation.

**Library usage:**
In this benchmark, we're not using any external libraries. However, if you were to include a library like Lodash (specifically, the `get()` method), it would simplify the code and provide an additional layer of abstraction for lookups.

**Special JS feature/syntax:**
This benchmark doesn't use any special JavaScript features or syntax beyond what's built-in to the language. However, if you were to add some advanced techniques like memoization (caching results) or lazy evaluation (only calculating values when needed), that would be an interesting variation to explore.

**Other alternatives:**

* **Set**: Another data structure to consider is a Set, which stores unique values and allows for efficient membership testing using the `has()` method. Using a Set might offer better performance than Maps in certain scenarios.
* **WeakMaps**: WeakMaps are a variant of Maps that store key-value pairs only when they're still referenced elsewhere in the code. This can be useful for memory-efficient caching or logging purposes.

Keep in mind that the choice between these data structures ultimately depends on your specific use case and performance requirements.

When preparing benchmarks, it's essential to consider factors like:

* Data size and distribution
* Access patterns (e.g., sequential vs random access)
* Memory constraints
* Cache behavior

Measuring different approaches can help you identify the most efficient solution for your particular problem.

Related benchmarks:

Map vs Object (w/delete) (version: 0)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: 5 years ago by: Guest

Jump to the latest result

Map lookup

Obj lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):