Benchmark: for vs foreach vs some vs every vs for..of vs map for large set

Script Preparation code:

var array = new Array(1000000);

Tests:

for
for (var i = 0; i < array.length; i++) { array[i]; }
foreach
array.forEach(function(i) { array[i]; });
some
array.some(function(i) { array[i]; });
every
array.every(function(i) { array[i]; });
for..of
for (var i of array) { array[i]; }
map
array.map(a => a);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
every
for..of
map

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested, compared, and their pros and cons.

**Benchmark Definition**

The benchmark is defined as a comparison of loop performance using different JavaScript constructs:

1. `for` loops
2. `forEach` method (an array method)
3. `some` method (an array method)
4. `every` method (an array method)
5. `for..of` loops (introduced in ECMAScript 2017)
6. `map` function (which can be used as a loop, but is not typically considered a loop)

**Test Cases**

Each test case represents a specific iteration of the benchmark, where one of the above loop types is compared against others.

Here's a brief explanation of each test case:

* `for`: A traditional `for` loop that iterates over an array using its length.
* `foreach`: The `forEach` method is called on the array, passing a callback function to execute for each element.
* `some`: The `some` method returns `true` if at least one element in the array satisfies the condition. In this case, the condition is simply accessing an element using its index.
* `every`: The `every` method returns `true` if all elements in the array satisfy the condition. Similar to `some`, but with a more restrictive evaluation.
* `for..of`: A new `for` loop iteration that uses the `of` keyword to iterate over the array elements directly.
* `map`: The `map` function is called on the array, which creates a new array with transformed versions of each element. This test case is used as a comparison point because it can be optimized to use SIMD instructions (Single Instruction, Multiple Data) for large arrays.

**Comparison and Performance**

The benchmark measures the performance of each loop type using various metrics:

* `ExecutionsPerSecond`: The number of iterations performed per second by each loop type.
* `Browser` and `DevicePlatform`: The browser and platform running the benchmark.
* `OperatingSystem`: The operating system used to run the benchmark.

**Pros and Cons**

Here's a brief summary of the pros and cons for each loop type:

* `for`: Simple, widely supported, but can lead to slower performance due to indexing and array bounds checks. **Cons**: Slower than other options.
* `forEach`: Easy to read and use, with good performance for arrays that don't need direct indexing. **Pros**: Readability, simplicity; **Cons**: May be slower for large arrays due to method overhead.
* `some` and `every`: Similar to `forEach`, but with more restrictive evaluation conditions. These methods can lead to faster performance when only one element needs to satisfy the condition. **Pros**: Fast for small sets; **Cons**: May not be suitable for larger arrays or strict evaluation requirements.
* `for..of`: A new, modern loop iteration that provides direct access to array elements without indexing. This can lead to significant performance gains for large arrays. **Pros**: Faster than traditional `for` loops; **Cons**: Limited browser support until ECMAScript 2017 adoption.
* `map`: Can be optimized for SIMD instructions on modern browsers, making it a competitive choice for large arrays. However, this requires careful optimization and may not work across all platforms. **Pros**: Potential for high performance with optimization; **Cons**: Requires manual optimization and platform-specific support.

**Library Usage**

In the benchmark, no libraries are explicitly mentioned, but some assumptions can be made based on the context:

* The `forEach`, `some`, and `every` methods rely on built-in array methods.
* The `map` function uses its own implementation.

**Special JS Features or Syntax**

The following special features are used in this benchmark:

* ECMAScript 2017's `for..of` loops
* SIMD instructions (not explicitly mentioned, but implied for the `map` test case)

Overall, the benchmark provides a comprehensive comparison of different loop types and array methods, highlighting performance differences and trade-offs between readability, simplicity, and optimization.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36

Browser/OS: Chrome 103 on Mac OS X 10.11.6

View result in a separate tab

Test name	Executions per second
for	3.8 Ops/sec
foreach	205.3 Ops/sec
some	204.8 Ops/sec
every	190.3 Ops/sec
for..of	5.8 Ops/sec
map	92.2 Ops/sec

Related benchmarks:

for vs foreach vs some vs every vs for..of vs map for large set (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs some vs every vs for..of vs map

Created: one year ago by: Registered User

Jump to the latest result

for

foreach

some

every

for..of

map

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):