Benchmark: different ways to loop

Script Preparation code:

var arr = [...new Array(10000)].map(() => Math.random());

Tests:

for
let sum = 0; for (let i = 0; i < arr.length; i++) { sum += arr[i]; }
for-of
let sum = 0; for (const x of arr) { sum += x; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
for-of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:124.0) Gecko/20100101 Firefox/124.0

Browser/OS: Firefox 124 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
for	58879.0 Ops/sec
for-of	14399.6 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The `Script Preparation Code` section defines an array of 10,000 random numbers, which will be used as input for the loop tests.

**Test Cases**

There are two test cases:

1. **"for"`**: This test case uses a traditional `for` loop to iterate over the array and sum up its elements.
2. **"for-of"`**: This test case uses an enhanced `for...of` loop to iterate over the array and sum up its elements.

**Loop Comparison**

The benchmark compares the execution performance of these two different loop approaches on a desktop browser (Firefox 124) running on Mac OS X 10.15.

Now, let's discuss the pros and cons of each approach:

**Traditional `for` Loop:**

Pros:

* More control over iteration variables
* Can be more efficient for specific use cases

Cons:

* Requires manual incrementation of the loop variable
* Can lead to magic numbers (e.g., hardcoding the array length)

**Enhanced `for...of` Loop:**

Pros:

* Less verbose and easier to read
* Eliminates the need for explicit loop variable management
* Automatically handles iteration limits

Cons:

* May have performance overhead due to additional indirections
* Can be less efficient in certain situations (e.g., when using a custom iterator)

**Other Considerations:**

* Both loops use the same array and calculation logic, which helps isolate the effects of loop syntax.
* The benchmark doesn't consider other factors that might impact performance, such as:
	+ Cache efficiency
	+ Branch prediction
	+ SIMD (Single Instruction, Multiple Data) instructions

Regarding libraries or special JavaScript features, there are none mentioned in this specific benchmark.

**Other Alternatives:**

For similar benchmarks, you could explore:

* Iterators and generators (e.g., using `for...of` with an iterator)
* Loop unrolling techniques
* Using optimized loop algorithms (e.g., for binary search or Fibonacci sequences)

In summary, this benchmark compares the performance of traditional `for` loops versus enhanced `for...of` loops in a simple iteration scenario.

Related benchmarks:

different ways to loop (version: 0)

Comparing performance of: for vs for-of

Created: 2 years ago by: Guest

Jump to the latest result

for

for-of

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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