Benchmark: for vs forEach - MeasureThat.net

Script Preparation code:

  var i,
      value,
      length,
      values = [],
      sum = 0,
      context = values;
  
  
  for (i = 0; i < 10000; i++) {
      values[i] = Math.random();
  }
  
  function add(val) {
      sum += val;
  }

Tests:

for cached length
length = values.length; for (i = 0; i < length; i++) { sum += values[i]; }
forEach
values.forEach( function(val) { sum += val; } );
forEach cached function
values.forEach( add );

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for cached length
forEach
forEach cached function

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**What is being tested?**

The provided JSON represents two benchmarking scenarios: `for vs forEach`. The first one, "for cached length", tests an optimized version of the classic `for` loop where the length variable is cached. The second one, "forEach", tests the standard `forEach` method for iterating over an array.

**Options being compared**

There are three options being compared:

1. **Optimized `for` loop with cached length**: This implementation avoids the overhead of recalculating the array length on each iteration.
2. **Standard `forEach` method**: This is a more modern and concise way to iterate over arrays, but it may incur additional overhead due to the need to access the callback function's context.
3. **Cached function version of `forEach`**: In this implementation, the callback function passed to `forEach` is cached, which may reduce the overhead associated with the standard `forEach` method.

**Pros and cons of each approach**

1. **Optimized `for` loop with cached length**:
	* Pros: Reduced overhead due to cached length calculation.
	* Cons: May not be as concise or readable for developers familiar with the standard `for` loop.
2. **Standard `forEach` method**:
	* Pros: More modern and concise syntax, reducing code verbosity.
	* Cons: Additional overhead due to callback function access.
3. **Cached function version of `forEach`**:
	* Pros: May reduce overhead associated with callback function access in the standard `forEach` method.
	* Cons: May not be as widely supported or understood by developers.

**Library usage**

None of the provided benchmarks explicitly use any external libraries. However, it's worth noting that if a library were used, it might impact the results of the benchmarking test.

**Special JavaScript features or syntax**

There are no special JavaScript features or syntax mentioned in the provided code snippets. The code uses standard JavaScript constructs and does not employ any experimental or proposal-level features.

**Other alternatives**

If you're interested in exploring alternative approaches to iterating over arrays, some options include:

1. **Array.prototype.reduce()**: A more functional programming-inspired approach that can be used for reducing array elements.
2. **Array.prototype.map()**: Similar to `forEach`, but returns a new array with transformed elements.
3. **Loops and manual indexing**: Using traditional loops with manual indexing (e.g., using `for` loops or `while` loops) is another way to iterate over arrays, although it may be less concise and error-prone.

Keep in mind that these alternatives might have different performance characteristics and trade-offs compared to the optimized `for` loop and `forEach` methods being tested.

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:54.0) Gecko/20100101 Firefox/54.0

Browser/OS: Firefox 54 on Windows

View result in a separate tab

Test name	Executions per second
for cached length	322.6 Ops/sec
forEach	649.9 Ops/sec
forEach cached function	654.0 Ops/sec

Related benchmarks:

for vs forEach (version: 0)

Comparing performance of: for cached length vs forEach vs forEach cached function

Created: 7 years ago by: Registered User

Jump to the latest result

for cached length

forEach

forEach cached function

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):