Benchmark: For Loops Teflora Test

Script Preparation code:

var numbers = [];
for(var i = 0; i < 10000; ++i)
  numbers[i] = Math.random();

Tests:

for loop i++
for(var i = 0; i < numbers.length; i++) numbers[i] = numbers[i] * 1.5;
for loop ++i
for(var i = 0; i < numbers.length; ++i) numbers[i] = numbers[i] * 1.5;
for loop ++i, cached length
const length = numbers.length; for(var i = 0; i < length; i++) numbers[i] = numbers[i] * 1.5;
while i--
var i = numbers.length; while(i--) numbers[i] = numbers[i] * 1.5;
while ++i
var i = -numbers.length; while(++i) numbers[-i] = numbers[-i] * 1.5;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for loop i++
for loop ++i
for loop ++i, cached length
while i--
while ++i

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:85.0) Gecko/20100101 Firefox/85.0

Browser/OS: Firefox 85 on Windows

View result in a separate tab

Test name	Executions per second
for loop i++	70972.2 Ops/sec
for loop ++i	70248.1 Ops/sec
for loop ++i, cached length	70415.5 Ops/sec
while i--	59512.2 Ops/sec
while ++i	60034.4 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 provided JSON and explain what is being tested, compared options, pros and cons, and other considerations.

**Benchmark Definition**

The benchmark definition consists of a script preparation code, which initializes an array `numbers` with 10,000 random values using `Math.random()`. The HTML preparation code is empty. This setup likely tests the performance of loops in JavaScript.

**Options Compared**

There are four options being compared:

1. **For loop i++**: In this option, the variable `i` is incremented using the post-increment operator (`++i`). This means that after each iteration, `i` is incremented by 1.
2. **For loop ++i**: Similar to the previous option, but the pre-increment operator (`++i`) is used instead of post-increment. This increments `i` before each iteration.
3. **For loop ++i, cached length**: In this option, a constant `length` is calculated and stored in memory using `numbers.length`. Then, the for loop uses the pre-increment operator (`++i`) to increment `i`.
4. **While i--** and **while ++i**: These two options use while loops instead of for loops. The variable `i` is decremented or incremented using the post-decrement and pre-increment operators (`--i` and `++i`, respectively).

**Pros and Cons**

Here's a brief summary of the pros and cons of each option:

* **For loop i++**: This approach may have better cache locality, as the increment operation can be optimized by the compiler. However, it may lead to slower performance due to the overhead of post-increment.
* **For loop ++i**: Similar to `i++`, but with pre-increment. It may be faster than `i++` due to reduced overhead, but cache locality might suffer.
* **For loop ++i, cached length**: By caching the length of the array, this approach avoids the overhead of calculating it every iteration. However, it introduces an additional memory allocation and potential cache thrashing issues.
* **While i--** and **while ++i**: These options use while loops instead of for loops, which can lead to longer loop iterations due to the nature of while loops (i.e., they continue as long as a condition is true). This might affect performance.

**Library Usage**

There doesn't appear to be any explicit library usage in this benchmark. However, the `Math.random()` function is used to generate random values for the array `numbers`.

**Special JS Features or Syntax**

No special JavaScript features or syntax are mentioned that require specific handling or configuration.

**Alternatives**

Other alternatives to measure loop performance could include:

1. **Array iterations**: Measure the time it takes to iterate through an array using a for loop, forEach method, or other iteration methods.
2. **Native browser optimizations**: Test the native browser's optimization of loops, such as inlining, unrolling, or fusion.
3. **Multithreading**: Measure the performance of concurrent loop execution using multiple threads or workers.

Note that these alternatives might require different benchmarking setups and configurations to achieve meaningful results.

Overall, this benchmark compares the performance of different loop iteration approaches in JavaScript, providing insights into cache locality, memory allocation, and compiler optimization strategies.

Related benchmarks:

For Loops Teflora Test (version: 0)

Comparing performance of: for loop i++ vs for loop ++i vs for loop ++i, cached length vs while i-- vs while ++i

Created: 3 years ago by: Guest

Jump to the latest result

for loop i++

for loop ++i

for loop ++i, cached length

while i--

while ++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):