Benchmark: for-in vs object.keysasdasdasd

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) { console.log(key); } }
Object.keys
for (var i=10000; i > 0; i--) { for (const key of Object.keys(obj)){ 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):

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Definition**

The provided benchmark definition represents a microbenchmark that tests two different approaches to iterating over an object in JavaScript:

1. **For-in loop**: This is a traditional approach where you use a `for` loop with an array-like object (in this case, `obj`) and iterate over its properties using the `key in obj` syntax.
2. **Object.keys() method**: This is a modern approach that uses the built-in `Object.keys()` method to get an array of the object's property names.

**Options Compared**

The benchmark compares two options:

* **For-in loop with traditional syntax (`for (var i=10000; i > 0; i--) { for (var key in obj) { console.log(key); } }`)**
* **Object.keys() method with const expression (`for (const key of Object.keys(obj)){ console.log(key); })`**

**Pros and Cons**

Here are the pros and cons of each approach:

1. **For-in loop**:
	* Pros:
		+ Wide browser support (older browsers may not have built-in `Object.keys()` method)
		+ Often used in legacy codebases
	* Cons:
		+ Can be slower due to its array-like nature (may involve creating arrays or iterating over properties multiple times)
2. **Object.keys() method**:
	* Pros:
		+ Faster and more efficient (only creates a single array of property names once)
		+ More modern and widely supported (modern browsers have built-in support for `Object.keys()` method)
	* Cons:
		+ May not work in older browsers without polyfills or transpilers

**Library and Special JS Features**

In this benchmark, the `Object.keys()` method is used with a constant expression (`const key of ...`). This syntax was introduced in ECMAScript 2015 (ES6) and allows for more concise and expressive code. The use of `Object.keys()` method without any additional libraries or imports makes it a built-in JavaScript feature.

**Other Alternatives**

If you wanted to test alternative approaches, here are some options:

* **Array.prototype.forEach()**: This is another way to iterate over an array (or object-like structure) in modern browsers.
* **for...of loop with Object.entries()**: This approach uses the `Object.entries()` method to get an array of key-value pairs and iterates over it using a `for...of` loop.

Keep in mind that these alternatives may have different performance characteristics or browser support, so they might not be suitable for all use cases.

Related benchmarks:

for-in vs object.keysasdasdasd (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):