Benchmark: Object VS new Map

Script Preparation code:

var a = [];
var b = {}
var map = new Map();

for (var i = 0; i < 5000; i++) {
    a.push(i);
    b[i] = `${i}`;
    map.set(i, i);
}

Tests:

Map
map.has(4500)
Object
b[4500]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map
Object

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser/OS: Chrome 125 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Map	19263064.0 Ops/sec
Object	19171034.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll explain what's being tested in the provided benchmark.

**Benchmark Test Case:**

The test case measures the performance difference between using an object (`b`) and a `Map` data structure to store key-value pairs. Both objects are populated with 5000 key-value pairs, where the key is the value itself (e.g., `{1: '1', 2: '2', ...}` for object `b`, and `i` as the key for each iteration in the map).

**Comparison Options:**

There are two options being compared:

1. **Object (`b`)**: This option uses a traditional JavaScript object to store key-value pairs.
2. **Map**: This option uses the built-in `Map` data structure, which is specifically designed for storing key-value pairs.

**Pros and Cons of Each Approach:**

* **Object (`b`)**:
	+ Pros:
		- Easy to use and understand.
		- Fast lookups (O(1) on average).
	+ Cons:
		- Not optimized for large amounts of data or frequent updates.
		- May lead to slower performance due to overhead from indexing and caching.
* **Map**:
	+ Pros:
		- Optimized for large amounts of data and frequent updates.
		- Provides faster lookups (O(1) on average).
		- Allows efficient iteration over the key-value pairs using `forEach()`, `entries()`, or `keys()`.
	+ Cons:
		- May require more code to set up and manage.
		- Less familiar to developers without experience with data structures.

**Other Considerations:**

* **Memory usage**: Maps typically use more memory than objects, especially for large datasets.
* **Performance overhead**: While maps are optimized for performance, they may introduce additional overhead due to the underlying data structure (e.g., hash tables).
* **Browser support**: Maps were introduced in ECMAScript 5, so they should work well in modern browsers. Objects, however, have been around since JavaScript's inception and are more widely supported.

**Library/Functionality:**

The benchmark uses the `Map` data structure, which is a built-in JavaScript object. It does not require any external libraries or dependencies.

**Special JS Features/Syntax:**

There is no specific JavaScript feature or syntax being used in this benchmark. The focus is on comparing the performance of using an object versus a map for storing key-value pairs.

**Alternatives:**

For those interested in exploring alternative data structures, some options include:

* **WeakMaps**: Similar to `Map`, but with additional features for handling weak references and garbage collection.
* **Set**: A data structure optimized for fast membership testing and insertion/deletion operations.
* **Array**: While not ideal for storing key-value pairs, arrays can be used in certain situations (e.g., when the values are numbers or strings).

Keep in mind that the choice of data structure ultimately depends on the specific requirements of your application and the trade-offs you're willing to make.

Related benchmarks:

Object VS new Map (version: 0)

Comparing performance of: Map vs Object

Created: 3 years ago by: Guest

Jump to the latest result

Map

Object

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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