Benchmark: Map vs Object non-contiguous integer keys

Script Preparation code:


window.objA = {};
window.mapA = new Map();
for (let i = 0; i < 1000; i++) {
	 const val = Math.floor(Math.random() * i * 32);
  	objA[String(val)] = true;
  	mapA.set(val, true);
}

Tests:

Read obj
for (const i in objA) { const b = objA[i]; }
Read map
for (const i in mapA) { const b = mapA.get(i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Read obj
Read map

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**What is being tested?**

The provided JSON represents two benchmark definitions for testing the performance of accessing elements in an object versus a Map data structure in JavaScript. The benchmarks are:

1. "Map vs Object non-contiguous integer keys"
2. Two individual test cases:
	* "Read obj" (accessing elements in an object using the `for...in` loop)
	* "Read map" (accessing elements in a Map using the `for...in` loop and the `get()` method)

**Options compared**

The benchmarks compare two approaches:

1. **Object access**: Using the `for...in` loop to iterate over the keys of an object (`objA`) and accessing the corresponding values.
2. **Map access**: Using the `for...in` loop to iterate over the keys of a Map (`mapA`) and accessing the corresponding values using the `get()` method.

**Pros and Cons**

* **Object access**:
	+ Pros: Simple, widely supported, and easy to implement.
	+ Cons: Can be slower for large objects due to the overhead of iterating over all properties, even if they're not accessed.
* **Map access**:
	+ Pros: Provides direct access to values without iterating over keys, which can be faster.
	+ Cons: Requires using the `get()` method, which might introduce additional overhead.

In general, Map access is expected to be faster for large datasets or when accessing elements by their key. However, in this specific benchmark, both approaches are relatively simple and may not exhibit significant performance differences.

**Library usage**

None of the benchmarks explicitly use a JavaScript library.

**Special JS feature/syntax (none mentioned)**

There's no special JavaScript feature or syntax used in these benchmarks. They rely solely on standard JavaScript features.

**Other alternatives**

If you were to rewrite these benchmarks using other approaches, consider the following alternatives:

* Using `Object.keys()` and `Array.prototype.forEach()` for object access
* Using `Object.values()` and `Array.prototype.forEach()` for object access (not shown in this benchmark)
* Using a library like Lodash or Ramda for more functional programming-style iteration

However, keep in mind that these alternatives might introduce additional overhead or change the nature of the benchmark.

In summary, MeasureThat.net's "Map vs Object non-contiguous integer keys" benchmark tests the performance of accessing elements in an object versus a Map data structure using simple `for...in` loops. While both approaches are straightforward, Map access is generally expected to be faster for large datasets or when accessing elements by their key.

Related benchmarks:

Map vs Object non-contiguous integer keys (version: 0)

Comparing performance of: Read obj vs Read map

Created: 4 years ago by: Registered User

Jump to the latest result

Read obj

Read map

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):