Benchmark: Array filter versus for loop

Script Preparation code:

var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59, 60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100], farr;
var len = 100;

Tests:

Filter
farr = arr.filter(function(item) { return (item>4); });
For
for (var i=0;i<len;i++) { if (arr[i]<5) continue; farr.push(arr[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Filter
For

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Measuring the performance of different JavaScript approaches can be quite fascinating.

The provided benchmark test case measures the execution time of two approaches to filter an array:

1.  **Array.filter() method**: This is a built-in JavaScript method that returns a new array with all elements that pass the test implemented by the provide function.
2.  **For loop**: A traditional, iterative approach using a for loop to iterate through the array and push elements to a new array if they meet a certain condition.

Now, let's break down each option:

**Array.filter() method:**

Pros:

*   **Concise and readable code**: The `filter()` method is often considered more concise and readable than manual iteration using a for loop.
*   **Built-in implementation**: Since it's a built-in JavaScript method, the browser takes care of optimizations and caching, which can lead to faster execution.

Cons:

*   **Limited control over iteration**: With the filter method, you have less control over how elements are iterated through and processed. This might be an issue if specific optimization strategies are required.
*   **Memory allocation overhead**: The `filter()` method creates a new array, which can lead to additional memory allocation.

**For loop:**

Pros:

*   **Fine-grained control**: With a for loop, you have direct access to the iteration variables and can optimize the loop more precisely, potentially leading to better performance.
*   **No memory allocation overhead**: By using a traditional array push approach, there's no additional memory allocation needed.

Cons:

*   **More verbose code**: For loops typically require more lines of code than the `filter()` method, making them less readable for some developers.
*   **Browser optimization limitations**: Since it's not a built-in JavaScript method, browsers might not optimize it as aggressively as they would with native methods like `filter()`.

**Library usage:**

In this case, no libraries are explicitly mentioned. However, the use of the `push()` method inside the loop could be seen as utilizing a library function if we consider `Array.prototype.push()`. While it's still a standard JavaScript function, some developers might argue that it introduces additional overhead due to its dynamic nature.

**Special JavaScript features:**

There are no special JavaScript features or syntaxes mentioned in this benchmark. Both approaches rely on the basic constructs of JavaScript (arrays, loops, conditional statements) and don't introduce any advanced concepts.

**Alternatives:**

Some alternative approaches for filtering arrays could include:

*   Using `Array.prototype.every()` method, which might provide a different performance profile compared to `filter()`.
*   Implementing a custom filtering algorithm using bitwise operations or other low-level optimizations.
*   Utilizing a third-party library optimized for filtering and iterating over large datasets.

These alternatives would require adjustments to the benchmark test cases to accommodate the new methods.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.102 Safari/537.36

Browser/OS: Chrome 98 on Windows

View result in a separate tab

Test name	Executions per second
Filter	1104416.5 Ops/sec
For	21361.6 Ops/sec

Related benchmarks:

Array filter versus for loop (version: 0)

Comparing performance of: Filter vs For

Created: 2 years ago by: Guest

Jump to the latest result

Filter

For

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):