Benchmark: object.keys vs length variable

Script Preparation code:

var obj = {};

Tests:

for-in
let length = 0; let id = 1; for (var i=10000; i > 0; i--) { obj[id] = []; id += 1; length +=1; }
Object.keys
let id = 1; for (var i=10000; i > 0; i--) { obj[id] = []; id += 1; } Object.keys(obj).length

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Object.keys

Fastest: N/A

Slowest: N/A

Latest 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, compared, and some pros and cons of each approach.

**Benchmark Overview**

The provided benchmark compares two ways to get the number of keys in an object: using `Object.keys()` and using a `for-in` loop. The test case creates an object with 10,000 properties and measures how many times each method can execute within a second.

**What's Being Tested**

* **Method 1: Using Object.keys()**
	+ The `Object.keys()` method returns an array of strings representing the property names of an object.
	+ The test case uses this method to measure the number of executions per second, by comparing the length of the resulting array to a pre-calculated value (`length` variable).
* **Method 2: Using for-in loop**
	+ The `for-in` loop iterates over the properties of an object using a loop variable (`i`) that increments from 0 to the length of the object.
	+ The test case uses this method to measure the number of executions per second, by incrementing a counter (`length` variable) for each iteration.

**Options Compared**

The benchmark compares two approaches:

* **Method 1: Object.keys()**
* **Method 2: For-in loop**

**Pros and Cons**

* **Object.keys():**
	+ Pros:
		- Fast and efficient, as it uses a built-in method.
		- Easy to read and maintain, as it uses a standard JavaScript API.
	+ Cons:
		- May have performance overhead due to the array creation step.
		- Limited control over iteration order (e.g., if the object has duplicate property names).
* **For-in loop:**
	+ Pros:
		- Allows for fine-grained control over iteration order and logic.
		- No overhead from array creation or method calls.
	+ Cons:
		- More complex and harder to read/maintain due to the manual loop variable management.
		- May be slower than using `Object.keys()` due to the iterative step.

**Library Usage**

There is no explicit library usage mentioned in the benchmark definition or test cases. However, note that `Object.keys()` is a built-in method of the JavaScript language.

**Special JS Features/Syntax**

* **ES6+ features:** None explicitly mentioned.
* **Other considerations:**
	+ Keep in mind that this benchmark measures performance, which can be influenced by factors such as:
		- Garbage collection frequency
		- Memory allocation and deallocation
		- CPU architecture and cache behavior

**Alternatives**

Some possible alternatives to these methods include:

* Using `JSON.stringify()` or `Object.entries()` instead of `Object.keys()`
* Using a different iteration approach, such as `for...of` loop (introduced in ES6+)
* Implementing custom iterator functions for more fine-grained control

Note that the choice of method ultimately depends on the specific requirements and constraints of your use case.

Related benchmarks:

object.keys vs length variable (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 4 years ago by: Guest

Jump to the latest result

for-in

Object.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):