Benchmark: Map vs Object (real-world) Performance (disabling object-specific optimizations and default keys)

Script Preparation code:

var keyCount = 16384
var keys = []
var map = new Map()
var obj = Object.create(null)
delete obj.x


// Hide lookup keys to prevent V8 cheating (AKA Optimizing)
var getConspicuousKey = seed => keys[Math.floor(seed * keyCount)]


// Setup out test objects w/ random values
for (let i=0; i<keyCount; i++) {
  let val = Math.random()
  let key = Math.random()
  keys.push(key)
  map.set(key,val)
  obj[key] = val
}

Tests:

Conspicuous Map lookup
for (let i=0; i<keyCount; i++) { let seed = Math.random() let key = getConspicuousKey(seed) a = map.get(key) }
Conspicuous Obj lookup
for (let i=0; i<keyCount; i++) { let seed = Math.random() let key = getConspicuousKey(seed) a = obj[key] }
Conspicuous Map lookup 2
for (let i=0; i<keyCount; i++) { let seed = Math.random() let key = getConspicuousKey(seed) a = map.get(key) }
Conspicuous Obj lookup 2
for (let i=0; i<keyCount; i++) { let seed = Math.random() let key = getConspicuousKey(seed) a = obj[key] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Conspicuous Map lookup
Conspicuous Obj lookup
Conspicuous Map lookup 2
Conspicuous Obj lookup 2

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 116 on Android

View result in a separate tab

Test name	Executions per second
Conspicuous Map lookup	62.7 Ops/sec
Conspicuous Obj lookup	47.2 Ops/sec
Conspicuous Map lookup 2	62.1 Ops/sec
Conspicuous Obj lookup 2	47.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring the performance of different data structures in JavaScript is crucial for developers to optimize their applications.

**Benchmark Overview**

The provided benchmark tests the performance of `Map` and `Object` data structures in JavaScript, specifically focusing on lookup operations with randomly generated keys. The benchmark simulates a real-world scenario by creating large datasets and measuring the execution time of various lookups.

**Options Compared**

Two main options are being compared:

1. **Conspicuous Map Lookup**: This option uses the `Map` data structure to perform a lookup operation with a randomly generated key.
2. **Conspicuous Object Lookup**: This option uses the `Object` data structure to perform a lookup operation with a randomly generated key.

**Pros and Cons of Each Approach**

1. **Conspicuous Map Lookup**
	* Pros:
		+ Maps are optimized for fast lookups, especially when using the `get()` method.
		+ This approach allows for efficient iteration over the map's entries.
	* Cons:
		+ The use of `Map` may lead to additional overhead due to its internal implementation details (e.g., hash tables).
2. **Conspicuous Object Lookup**
	* Pros:
		+ Objects are lightweight and easy to work with, especially for small datasets.
		+ This approach allows for direct access to properties without the need for a separate lookup mechanism.
	* Cons:
		+ Object lookups can be slower than map lookups, especially when dealing with large datasets.

**Library Used**

In this benchmark, `Map` is used as the data structure for fast lookups. The `get()` method is specifically used to perform the lookup operation.

**Special JS Feature or Syntax**

This benchmark uses a feature called "conspicuous key" which means that when using the `Math.random()` function in combination with the `keyCount` variable, it creates a random key and assigns it to an array of keys (`keys`) for better distribution. This is done to prevent any potential optimization by V8 (Chrome's JavaScript engine) by hiding the lookup keys.

**Other Considerations**

When choosing between `Map` and `Object`, consider the following factors:

* **Data size**: For large datasets, `Map` might be more efficient due to its optimized hash table implementation.
* **Lookup frequency**: If you need to perform frequent lookups, use `Map`.
* **Code readability**: Use `Object` when code readability is more important than performance.

**Other Alternatives**

If you're looking for alternative data structures in JavaScript, consider:

1. **WeakMaps**: Similar to regular maps but allow for garbage collection of keys.
2. **Sets**: Used for fast membership testing and deletion operations.
3. **Sorted Maps/Objects**: Provide efficient iteration and insertion orders.

These alternatives might be more suitable depending on the specific use case and requirements.

Related benchmarks:

Map vs Object (real-world) Performance (disabling object-specific optimizations and default keys) (version: 0)

Lookup of map vs object (in a real-world test format)

Comparing performance of: Conspicuous Map lookup vs Conspicuous Obj lookup vs Conspicuous Map lookup 2 vs Conspicuous Obj lookup 2

Created: one year ago by: Guest

Jump to the latest result

Conspicuous Map lookup

Conspicuous Obj lookup

Conspicuous Map lookup 2

Conspicuous Obj lookup 2

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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