Benchmark: for-in own keys vs object.keys

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in
for (var i=10000; i > 0; i--) { for (var key in obj) { if(Object.hasOwnProperty.call(obj,key)){ console.log(key); } } }
Object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(key)); }

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):

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**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmarking test case on MeasureThat.net. The benchmark compares the performance of two approaches: using `for...in` loops and using `Object.keys()` functions.

**What is being tested?**

In this benchmark, we are testing how quickly two different methods can iterate over the keys of an object:

1. **For-in loop**: Using a traditional `for...in` loop to iterate over the object's properties.
2. **Object.keys() function**: Using the built-in `Object.keys()` function to get an array-like object containing the enumerable property names of an object.

**Options compared**

The two options being compared are:

* **For-in loop**: This traditional approach iterates over the object's properties using a loop that checks each property name.
* **Object.keys() function**: This modern approach uses a built-in function to get an array-like object containing only the enumerable property names of an object.

**Pros and Cons**

Here are some pros and cons of each approach:

* **For-in loop**:
	+ Pros: Can be used in older browsers, doesn't rely on `Object.keys()` function.
	+ Cons: Can iterate over non-enumerable properties (i.e., properties that don't have a name), can be slower due to the loop overhead.
* **Object.keys() function**:
	+ Pros: Only iterates over enumerable properties, is generally faster and more concise than traditional loops.
	+ Cons: Requires modern browsers that support `Object.keys()`.

**Library usage**

There is no explicit library usage in this benchmark. However, if we were to analyze the code further, we might notice that the `Object.hasOwnProperty.call()` function is used in both benchmarks. This function is a built-in method of the JavaScript `Object` prototype and doesn't rely on any external libraries.

**Special JS feature or syntax**

There are no special JavaScript features or syntax used in this benchmark beyond what's standard for modern JavaScript development (ES6+).

**Other alternatives**

If we were to consider other alternatives, here are a few:

* **Looping using `forEach()`**: This approach uses the `forEach()` method on an array-like object created by `Object.keys()`. While it achieves similar results, it might incur additional overhead due to the function call and iteration.
* **Using `for...of` loop**: Instead of using traditional loops or `Object.keys()`, we could use a modern `for...of` loop to iterate over the object's properties. This approach is more concise but still relies on the `Object.keys()` function.

Overall, this benchmark provides a clear comparison between two common approaches to iterating over an object's keys in JavaScript: traditional `for-in` loops and using the `Object.keys()` function.

Related benchmarks:

for-in own keys vs object.keys (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):