Benchmark: const in a for loop

Script Preparation code:

var people = [{name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}, {name: 'a', age:1}]

Tests:

using const in for
const morePeople = []; for (const p of people){ morePeople.push(p); }
simple normal usage
const morePeople = []; for (p of people){ morePeople.push(p); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
using const in for
simple normal usage

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36

Browser/OS: Chrome 123 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
using const in for	16596179.0 Ops/sec
simple normal usage	643309.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

The provided JSON represents two benchmark definitions:

1. **"const in a for loop"**: This benchmark measures the performance of using `const` with the `of` operator in a `for` loop. The script preparation code creates an array `people` with 12 elements and assigns it to another variable `morePeople`, which is initialized as an empty array. The benchmark definition itself uses `const` with the `of` operator to iterate over the `people` array and push each element onto the `morePeople` array.
2. **"simple normal usage"**: This benchmark measures the performance of using a traditional `for` loop without `const`. It's similar to the first benchmark, but without the `const` keyword.

Now, let's explore the options compared in these benchmarks:

* **Using `const` with `of` vs. traditional `for` loop**:
	+ Pros of using `const` with `of`: It can lead to better performance due to reduced overhead from reassigning variables inside the loop.
	+ Cons: The `of` operator was introduced in ECMAScript 2019, and not all browsers support it yet. Additionally, some older JavaScript engines might not optimize this syntax as well as traditional loops.
* **Traditional `for` loop vs. `for...of` loop**:
	+ Pros of traditional `for` loop: It's a widely supported and well-established construct, making it easier to understand and maintain for developers familiar with older codebases.
	+ Cons: Traditional loops can be slower due to the reassignment of variables inside the loop.

Other considerations:

* **Array iteration**: Both benchmarks use arrays as the data structure. However, other data structures like objects or sets might have different performance characteristics when iterating over them.
* **Browser-specific optimizations**: Different browsers may optimize JavaScript engine internals in unique ways, leading to variations in benchmark results across platforms.

Now, let's look at the provided benchmark result:

The latest benchmark result shows two test cases with different execution rates. The "using const in for" test case has a higher executions per second (16596179.0) compared to the "simple normal usage" test case (643309.375). This suggests that using `const` with the `of` operator can lead to improved performance in this specific benchmark.

As for libraries or special JavaScript features, none are explicitly mentioned in the provided code snippets. However, it's essential to note that other libraries like Lodash might be used indirectly through array methods or other dependencies.

The MeasureThat.net website provides a range of alternative benchmarks and test cases, allowing users to explore different aspects of JavaScript performance and optimization.

Related benchmarks:

const in a for loop (version: 0)

Comparing performance of: using const in for vs simple normal usage

Created: 8 months ago by: Guest

Jump to the latest result

using const in for

simple normal usage

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):