Benchmark: For Loops Teflora Test 2

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 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1 Safari/605.1.15

Browser/OS: Safari 14 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for loop i++	478.2 Ops/sec
for loop ++i	477.5 Ops/sec
for loop ++i, cached length	715.3 Ops/sec
while i--	719.0 Ops/sec
while ++i	720.5 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!

**Benchmark Definition:**
The benchmark definition is a JSON object that describes the test to be performed. In this case, it's a simple for loop that multiplies each element in an array by 1.5. The array `numbers` is populated with random numbers using another script.

**Script Preparation Code:**
The script preparation code is responsible for initializing the `numbers` array with 10,000 random numbers.

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

This code creates an empty array and then uses a for loop to populate it with 10,000 random numbers. The `Math.random()` function generates a random number between 0 (inclusive) and 1 (exclusive).

**Options Compared:**
The benchmark compares four different approaches:

1. **For Loop i++**: This approach increments the loop counter variable (`i`) after each iteration.
2. **For Loop ++i**: This approach increments the loop counter variable (`i`) before each iteration.
3. **For Loop ++i, Cached Length**: This approach uses a cached length value to avoid repeated calculations of `numbers.length`.
4. **While i--**: This approach uses a while loop with decrementing counter variable (`i`).
5. **While ++i**: This approach uses a while loop with incrementing counter variable (`i`).

**Pros and Cons:**

* **For Loop i++**: This approach is likely to be the fastest since it avoids the overhead of incrementing a variable after each iteration.
* **For Loop ++i**: This approach may be slower than `i++` due to the additional overhead of incrementing before each iteration.
* **For Loop ++i, Cached Length**: This approach can improve performance by avoiding repeated calculations of `numbers.length`.
* **While i--** and **While ++i**: These approaches are likely to be slower than for loops since they use a while loop with decrementing/incrementing counter variables.

**Other Considerations:**

* The benchmark only measures the execution time, which is not always an accurate metric. Other factors like memory allocation, garbage collection, and caching can affect performance.
* The use of `Math.random()` to generate random numbers may introduce some overhead due to its implementation details (e.g., using a linear congruential generator).
* The benchmark does not account for other optimization techniques that might be used by the JavaScript engine, such as inlining, memoization, or optimization of specific library functions.

**Library:**
The `numbers` array is an example of an array, which is a fundamental data structure in JavaScript. Arrays are used to store collections of values and provide methods like indexing, slicing, and iteration.

**Special JS Feature/Syntax:**
There are no special JavaScript features or syntax elements explicitly mentioned in the benchmark definition or options compared. However, the use of `var` with `++` and `--` operators implies that this code is intended for older versions of JavaScript (pre ES6) where `let` and `const` were not yet introduced.

**Alternatives:**
Some alternative approaches to measure performance in JavaScript include:

* Using a profiler like Chrome DevTools or Node.js Inspector to analyze the execution time of specific functions or modules.
* Implementing a benchmarking framework like Benchmark.js or jsperf to automate benchmarking and compare different implementations.
* Using benchmarking libraries like micro-benchmark or perf-bench to measure performance in a more controlled environment.

Related benchmarks:

For Loops Teflora Test 2 (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):