Benchmark: for-in vs object.keys no cycle

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--) { let arr = []; for (var key in obj) { arr.push(key); } console.log(arr); }
Object.keys
for (var i=10000; i > 0; i--) { console.log(Object.keys(obj)); }

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

**Benchmark Overview**

The benchmark is designed to compare two approaches for iterating over an object in JavaScript:

1. Using `for...in` loop
2. Using `Object.keys()` method

**What are we comparing?**

In the test cases, we have two identical arrays (`obj`) with 7 properties ( `'a'` to `'g'`). We're interested in measuring which approach is faster and more efficient.

**Options compared:**

We're comparing:

* `for...in` loop
* `Object.keys()` method

**Pros and Cons of each approach:**

1. **`for...in` loop:**
	* Pros:
		+ More flexible, as it can be used with any object that supports the `in` operator.
		+ Can iterate over both enumerable and non-enumerable properties.
	* Cons:
		+ Can iterate over prototype chains, which may not be desirable in some cases.
		+ May have performance implications due to the overhead of property iteration.
2. **`Object.keys()` method:**
	* Pros:
		+ Returns an array of only enumerable properties.
		+ Does not iterate over prototype chains.
		+ Is a more modern and concise approach.
	* Cons:
		+ Only works with objects that have enumerable properties (some built-in objects may not).
		+ May be slower than `for...in` loop due to the overhead of creating an array.

**Library usage:**

In this benchmark, there is no explicit library usage. The script and HTML preparation codes are simple JavaScript snippets that create a sample object (`obj`) for testing.

**Special JS features or syntax:**

There are no special JavaScript features or syntax used in these test cases. They're straightforward, vanilla JavaScript code.

**Other alternatives:**

If you'd like to explore alternative approaches, here are a few:

1. **`forEach()` method:** While not directly related to `for...in` loop, `forEach()` can be used to iterate over an array of object properties.
2. **`Array.prototype.reduce()` method:** Another approach would be to use `reduce()` to iterate over the object's properties and accumulate a result.
3. **Using `Object.entries()` and `Map` data structure:** You could also explore using `Object.entries()` to get an array of key-value pairs, then using a `Map` to iterate over the values.

Keep in mind that these alternatives might have their own performance implications or trade-offs, and may not be as straightforward as the original `for...in` loop or `Object.keys()` method.

Related benchmarks:

for-in vs object.keys no cycle (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):