Benchmark: Array Entries vs fori

Script Preparation code:

var as = [];
for (var i = 0; i < 10000; i++) {
  as.push(Math.floor(Math.random() * 1000));
}

Tests:

Array.entries
const res = []; for(const a of as.entries()) res.push(a);
Array for i
const res = []; for(let i = 0; i < as.length; i++) { const a = as[i]; res.push(a); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.entries
Array for i

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36

Browser/OS: Chrome 116 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.entries	22995.7 Ops/sec
Array for i	1489.7 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Purpose**

The benchmark is designed to compare two approaches for accessing elements in an array: using the `entries()` method versus a traditional `for` loop with indexing (`i`).

**Options Compared**

Two options are compared:

1. **Array.entries()**: This option uses the `entries()` method, which returns an iterator object that yields pairs of values - the key (index) and the value (array element) - for each element in the array.
2. **Traditional `for` loop with indexing (`i`)**: This option uses a traditional `for` loop to iterate over the array elements, where `i` is the index of the current element.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Array.entries()**:
	+ Pros:
		- More concise and expressive code
		- Less error-prone, as the iterator object handles indexing automatically
	+ Cons:
		- May have performance overhead due to the creation of an iterator object
		- Not all browsers support `entries()` method (although most modern ones do)
* **Traditional `for` loop with indexing (`i`)**:
	+ Pros:
		- Wide browser support, as it's a standard `for` loop syntax
		- Often faster, since it avoids the overhead of creating an iterator object
	+ Cons:
		- More verbose and error-prone code
		- Indexing must be done manually, which can lead to mistakes

**Library/Additional Features**

There is no external library used in this benchmark. However, some modern JavaScript engines may have additional features or optimizations that affect performance.

**Special JS Feature/Syntax**

No special JavaScript feature or syntax is used in these test cases. Both approaches are standard and widely supported.

**Alternatives**

Other alternatives to compare in a similar benchmark might include:

* Using `forEach()` method instead of traditional `for` loop
* Using `map()` function instead of indexing and pushing elements to an array
* Using `reduce()` function instead of traditional accumulation (e.g., summing or accumulating values)

Keep in mind that the choice of approach depends on the specific use case, performance requirements, and personal preference.

Related benchmarks:

Array Entries vs fori (version: 0)

Comparing performance of: Array.entries vs Array for i

Created: 3 years ago by: Guest

Jump to the latest result

Array.entries

Array for i

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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