Benchmark: Object.keys.length vs for in 2

Script Preparation code:

var testData = {
    toto: 'titi'
};
function testEmptyObject(obj) {
    for (var key in obj) {
        return false;
    }
    return true;
}

Tests:

object keys
Object.keys(testData).length === 0
for in
testEmptyObject(testData)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
object keys
for in

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 25 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
object keys	86167208.0 Ops/sec
for in	114947104.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The MeasureThat.net website provides a platform for creating and running JavaScript microbenchmarks. The provided benchmark involves two test cases: "object keys" and "for in".

**Test Case 1: object keys**

This test case measures the performance of using `Object.keys()` to get the length of an empty object.

In the script preparation code, an empty object `testData` is created with a single property `toto`. The `Object.keys()` function is used to get the array of own enumerable properties of the object. Since the object is empty, the length of the resulting array should be 0.

The benchmark definition checks if the length of the returned array from `Object.keys()` is equal to 0.

**Test Case 2: for in**

This test case measures the performance of using a traditional `for` loop with `in` to iterate over the properties of an object.

In the script preparation code, another empty object `testData` is created. A function `testEmptyObject()` is defined that uses a traditional `for` loop with `in` to iterate over the properties of the object. The loop checks if any property exists; if not, it returns false. If all properties exist, it returns true.

The benchmark definition checks the return value of the `testEmptyObject()` function.

**Options Compared**

Two options are being compared:

1. **Using `Object.keys()`**: This method is used to get the length of an object.
2. **Traditional `for` loop with `in`**: This approach uses a traditional loop to iterate over the properties of an object and checks for existence.

**Pros and Cons of Each Approach**

* **Using `Object.keys()`**:
	+ Pros: concise, efficient, and well-supported by modern browsers.
	+ Cons: may not work in older browsers or IE versions prior to 9. Additionally, it may have slower performance compared to traditional loop approaches due to the overhead of function calls.
* **Traditional `for` loop with `in`**:
	+ Pros: widely supported across all browsers and versions, can be more efficient for certain use cases (e.g., when working with large datasets).
	+ Cons: less concise, may require additional checks for existence.

**Library Used**

None, as this is a native JavaScript implementation.

**Special JS Feature or Syntax**

The benchmark uses the `in` operator to check for property existence in objects. This operator is a built-in feature of JavaScript and has been supported since its inception.

**Other Alternatives**

For measuring performance in JavaScript, other alternatives include:

1. **Benchmark.js**: A popular benchmarking library specifically designed for JavaScript.
2. **Benchmark.com**: A web-based platform that allows users to create and run benchmarks using various frameworks.
3. **jsbench**: An online platform for running JavaScript benchmarks.

Keep in mind that each alternative has its own strengths and weaknesses, and the choice of which one to use depends on your specific needs and requirements.

Related benchmarks:

Object.keys.length vs for in 2 (version: 0)

Comparing performance of: object keys vs for in

Created: 3 years ago by: Guest

Jump to the latest result

object keys

for in

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):