Benchmark: map over Object (or Record in TS) vs Map clone

Tests:

Obj / Object.entries()
let obj = {}; for (let i = 0; i < 1000000; i++) { obj[i] = i; } let tuples = Object.entries(obj).map(([k, v]) => [k, v]);
Map / spread
let map = new Map(); for (let i = 0; i < 1000000; i++) { map.set(i, i); } let tuples = [...map].map(([k, v]) => [k, v]);
Map / Array.from()
let map = new Map(); for (let i = 0; i < 1000000; i++) { map.set(i, i); } let tuples = Array.from(map).map(([k, v]) => [k, v]);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Obj / Object.entries()
Map / spread
Map / Array.from()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Obj / Object.entries()	6.2 Ops/sec
Map / spread	7.5 Ops/sec
Map / Array.from()	7.7 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

The benchmark represented in the provided JSON is focused on comparing different methods of iterating over and converting data structures in JavaScript, specifically between native Objects (or Records in TypeScript) and the built-in Map object. The core operations being tested are the conversion of these data structures into an array of key-value pairs, represented as tuples, using different approaches.

### Test Cases Overview

1. **Object / Object.entries()**
   - **Benchmark Code**: This test initializes a plain JavaScript object (`obj`) with 1,000,000 key-value pairs, where the keys are integers from 0 to 999,999 and the values are the same integers. Then it uses `Object.entries()` to convert this object into an array of tuples.
   - **Pros**: 
     - Simple and straightforward approach for converting an object into an array.
     - `Object.entries()` is a built-in and widely supported method.
   - **Cons**:
     - Performance can be slower compared to Map, especially when the object is large - as indicated by the benchmark results.
     - Objects do not maintain insertion order of keys in older JavaScript versions, although this is less of an issue with modern engines.

2. **Map / spread**
   - **Benchmark Code**: This test uses a `Map` to store 1,000,000 key-value pairs, similar to the object test. It then utilizes the spread operator (`...`) to convert the Map into an array of tuples.
   - **Pros**:
     - Maps maintain insertion order, which can be beneficial when the order of elements is important.
     - The spread operator is a very clean syntax for converting Maps to arrays.
   - **Cons**:
     - The performance can vary based on the JavaScript engine and the specific use case.
     - More overhead than using a simple object for cases where key order is not important.

3. **Map / Array.from()**
   - **Benchmark Code**: Similar to the previous test, this uses a `Map` but converts it into an array with `Array.from()`.
   - **Pros**:
     - `Array.from()` is explicit about converting iterable objects into arrays and can be more flexible with additional mapping functions.
     - Retains the insertion order of keys.
   - **Cons**:
     - Slightly more verbose than the spread operator for this specific case, potentially leading to slightly less readability at a glance.

### Performance Results

The benchmark results indicate that among the tested methods, the `Map / Array.from()` approach yielded the highest number of executions per second, suggesting that it might be the most efficient option for converting a Map to an array of tuples. The `Map / spread` was slightly slower but still performs better than using `Object.entries()` on the plain object. The plain object approach was the slowest, which aligns with the expectation that converting a large object could have more overhead than that of a Map.

### Summary of Considerations

- **Performance**: If performance is critical, especially with large datasets, Maps may provide better results.
- **Syntax and Readability**: The choice between the spread operator and `Array.from()` is largely a matter of personal preference and readability for the given context.
- **Use Cases**: Consider whether the application requires maintaining order or speed of operations. If insertion order is crucial, Maps should be favored.

### Alternatives

Other approaches for similar operations might include:

- **For-Loop Iteration**: Manually iterating over the keys of an object using a `for` loop can sometimes yield better performance in specific cases, especially when optimized for the particular dataset.
- **Reduce Method**: Using the `Array.prototype.reduce()` method could also be an alternative way of transforming objects into arrays, although it might not be as straightforward and have more overhead.
- **Libraries**: Utility libraries like Lodash can provide functions for similar transformations that might be optimized for performance and cross-browser compatibility, though they would introduce an additional dependency.

Overall, this benchmark helps highlight performance considerations when choosing between ordinary objects and Maps in JavaScript for similar operations.

Related benchmarks:

map over Object (or Record in TS) vs Map clone (version: 1)

Comparing performance of: Obj / Object.entries() vs Map / spread vs Map / Array.from()

Created: one month ago by: Guest

Jump to the latest result

Obj / Object.entries()

Map / spread

Map / Array.from()

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):