Benchmark: for-in vs object.keys v3

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

var map = new Map();
for (const k in obj) {
  map.set(k, obj[k]);
}

Tests:

for-in
for (let i=10000; i > 0; i--) { for (const key in obj) { console.log(key); } }
Map.keys
for (let i=10000; i > 0; i--) { for (const key of map.keys()) { console.log(key); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Map.keys

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 break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark is testing two approaches to iterate over an object:

1. `for-in`: Using a traditional `for` loop with `in` keyword to access object properties.
2. `Map.keys()`: Using the `keys()` method of a JavaScript `Map` object to get an iterator over its entries.

**Options Compared**

The benchmark is comparing the performance of these two approaches:

* **For-in**: Iterates directly over the object's properties using the `in` keyword, which may not be the most efficient way.
* **Map.keys()**: Uses the `keys()` method to get an iterator over the map's entries, which is a more modern and efficient approach.

**Pros and Cons**

* **For-in**:
	+ Pros: Simple and widely supported, no additional library required.
	+ Cons: May not be the fastest way due to indirect iteration and potential property access overhead.
* **Map.keys()**:
	+ Pros: More efficient and direct iterator over entries, better suited for large datasets.
	+ Cons: Requires a `Map` object, which may add an extra step in setup.

**Library and Purpose**

In the provided benchmark definition, two libraries are used:

1. `Map`: A built-in JavaScript data structure that stores mappings of keys to values.
2. No external library is required for either test case.

**Special JS Feature or Syntax**

There's no special feature or syntax being tested in this benchmark. It only uses standard JavaScript constructs and features.

**Other Alternatives**

If you wanted to explore other approaches, here are a few alternatives:

* Using `Object.entries()` (ES2015+): Iterate directly over an object's entries using the `entries()` method.
* Using `Array.prototype.forEach()`: Convert the object's properties into an array and use `forEach()` to iterate over it.
* Using `reduce()`: Use the `reduce()` method to accumulate values from an object's properties.

Keep in mind that these alternatives may have different performance characteristics or requirements, so it's essential to test them specifically for your use case.

Related benchmarks:

for-in vs object.keys v3 (version: 0)

Comparing performance of: for-in vs Map.keys

Created: 4 years ago by: Guest

Jump to the latest result

for-in

Map.keys

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):