Benchmark: Array filter vs. for loop - with for in zz

Script Preparation code:

var arr = Array.from(Array(100000), () => (Math.random() * 10) |0)

Tests:

Filter
arr.filter(function(item) { return (item>4); });
For
let farr=[]; for (var i=0,len=arr.length;i<len;i++) { if (arr[i]>4) farr.push(arr[i]); }
In place for
let farr=[]; let next = 0; for (var i=0,len=arr.length;i<len;i++) { if (arr[i]>4) farr[next++] = arr[i]; } farr.splice(next);
in place, temp var for value
let farr=[]; let next = 0; for (var i=0,len=arr.length;i<len;i++) { let val = arr[i] if (val>4) farr[next++] = val; } farr.splice(next);
filter, arrow funcs
arr.filter(item => item>4)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Filter
For
In place for
in place, temp var for value
filter, arrow funcs

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance!

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

**Benchmark Overview**

The benchmark compares four different approaches to filter an array of 100,000 elements:

1. `Array.prototype.filter()`
2. A traditional `for` loop
3. An in-place `for` loop with a temporary variable
4. An arrow function version of the `filter()` method

**Tested Options**

The benchmark tests these four options against each other to determine which one performs best.

Pros and Cons:

* **Array.prototype.filter()**: This is a built-in method that creates a new array with all elements that pass the test implemented by the provided function. It's concise and readable, but may incur additional memory overhead.
* **Traditional `for` loop**: This approach iterates over the array using an index variable, checking each element against the condition. It's more control-oriented but can be less efficient due to the need for manual indexing.
* **In-place `for` loop with a temporary variable**: This variant uses a single variable to store filtered elements and avoids creating a new array. However, it may introduce additional overhead due to the need to manage the variable.
* **Arrow function version of filter()**: This is a concise and readable way to implement the `filter()` method using an arrow function. It's likely to be comparable in performance to the built-in implementation.

**Library Usage**

None of the benchmarked options explicitly use any external libraries, but it's worth noting that JavaScript engines may have internal optimizations or micro-optimizations that affect performance.

**Special JS Feature/Syntax**

The benchmark uses a feature called "template literals" (`\r\n`) in the `Script Preparation Code` section. This is a modern JavaScript syntax that allows for more readable and efficient string interpolation. However, older JavaScript engines might not support it or may have different behavior.

**Other Alternatives**

There are other ways to filter an array, such as:

* Using `Array.prototype.map()` and `Array.prototype.filter()`
* Using `Set` data structure to keep track of unique elements
* Using a custom implementation with bitwise operations (although this is likely to be less efficient)

The benchmark provides a controlled comparison of these approaches, allowing users to understand the performance characteristics of each option.

When interpreting the results, consider factors such as:

* Memory usage: How much memory does each approach allocate?
* Execution time: What's the performance impact of each approach on your specific use case?

Keep in mind that the benchmark is designed to provide a general understanding of performance differences between these approaches. The actual performance impact will depend on your specific code, hardware, and JavaScript engine version.

Related benchmarks:

Array filter vs. for loop - with for in zz (version: 0)

Comparing performance of: Filter vs For vs In place for vs in place, temp var for value vs filter, arrow funcs

Created: 3 years ago by: Registered User

Jump to the latest result

Filter

For

In place for

in place, temp var for value

filter, arrow funcs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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