Benchmark: all variety of loops in js

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = i;
    }
  
    function someFn(i) {
      return i * 3 * 8;
    }

Tests:

foreach
arr.forEach(function (item){ someFn(item); })
for++
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
map
arr.map(item => someFn(item))
for of
for (var value of arr) { someFn(value); }
for in
for (var i in arr) { someFn(arr[i]); }
filter
arr.filter(item => someFn(item))
reduce
arr.reduce(item => someFn(item))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for++
map
for of
for in
filter
reduce

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 19 hours ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
foreach	2096810.4 Ops/sec
for++	582987.4 Ops/sec
map	517617.7 Ops/sec
for of	749504.7 Ops/sec
for in	67703.2 Ops/sec
filter	431981.8 Ops/sec
reduce	760046.2 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmarking data and explain what's being tested, compared, and their pros/cons.

**Benchmark Definition JSON:**

The benchmark definition json represents a JavaScript microbenchmark that tests various loop constructs in JavaScript.

**What's Being Tested:**

The benchmark tests six different loop constructs:

1. `forEach`: Using the `Array.prototype.forEach` method.
2. `for++`: Using a traditional `for` loop with incrementing the variable `i`.
3. `map`: Using the `Array.prototype.map` method.
4. `for of`: Using the `for...of` loop syntax.
5. `for in`: Using the `for...in` loop syntax.
6. `filter` and `reduce`: Not explicitly mentioned, but implied by the context.

**Options Compared:**

The benchmark compares these six loop constructs to determine which one is the fastest.

**Pros and Cons of Each Approach:**

1. `forEach`:
	* Pros: Simple, concise, and widely supported.
	* Cons: May be slower due to its iteration overhead.
2. `for++`:
	* Pros: Familiar syntax for many developers, easy to optimize manually.
	* Cons: Can be error-prone, especially with complex loop conditions.
3. `map`:
	* Pros: Returns a new array with the mapped values, making it more predictable.
	* Cons: May incur additional memory allocations and copies.
4. `for of`:
	* Pros: Modern syntax that avoids explicit variable indexing.
	* Cons: Less familiar to older developers and those without experience with ES6+ features.
5. `for in`:
	* Pros: Allows iterating over object properties using the property name.
	* Cons: Can be slower due to its iteration overhead and potential for infinite loops.
6. `filter` and `reduce` (implied):
	* These methods are not explicitly tested, but their performance is affected by the input data size and complexity.

**Library Usage:**

None of the provided benchmark definitions use any external libraries.

**Special JS Features/Syntax:**

The benchmark utilizes ES6+ features such as:

1. `Array.prototype.forEach`
2. `for...of` loop syntax
3. `Array.prototype.map`
4. `const` and `let` declarations (not explicitly mentioned, but implied by the context)

**Other Considerations:**

When writing microbenchmarks like this one, consider the following best practices:

1. Use a simple, well-defined test case that isolates the performance difference you're trying to measure.
2. Avoid external dependencies and use built-in JavaScript functions whenever possible.
3. Ensure your benchmark is representative of real-world usage patterns.
4. Consider using a more advanced benchmarking library or tool for more accurate results.

**Alternatives:**

If you need to compare performance between loop constructs in JavaScript, consider using other benchmarking tools and libraries, such as:

1. jsperf
2. Benchmark.js
3. WebPageTest

These tools provide more comprehensive features and accuracy than a simple manual benchmark like the one provided.

Related benchmarks:

all variety of loops in js (version: 0)

Comparing performance of: foreach vs for++ vs map vs for of vs for in vs filter vs reduce

Created: 4 years ago by: Guest

Jump to the latest result

foreach

for++

map

for of

for in

filter

reduce

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):