Benchmark: for vs foreach vs some vs for..of 1

Script Preparation code:

var array = new Array(100000);

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]; });
for..of
for (var i of array) { array[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
for..of

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's dive into explaining the JavaScript microbenchmark, MeasureThat.net.

**What is being tested?**

MeasureThat.net is comparing the performance of four different loop constructs:

1. Traditional `for` loop (`var i = 0; i < array.length; i++)`
2. `forEach` method (`array.forEach(function(i) { ... })`)
3. `some` method (`array.some(function(i) { ... })`)
4. `for...of` loop (`for (var i of array) { ... }`)

These loops are designed to iterate over an array and execute a block of code for each element.

**Options being compared**

The comparison focuses on the execution speed of these four loop constructs. Each test case measures how many times a given browser instance executes the loop body within a second, which is represented by `ExecutionsPerSecond` value in the benchmark results.

**Pros and Cons of different approaches:**

1. **Traditional `for` loop**: This is a straightforward loop construct that can be easily understood and optimized for performance. However, it requires manual indexing (`array[i]`) which might lead to issues if the array index is not properly managed.
2. **`forEach` method**: The `forEach` method provides an elegant way to iterate over arrays, but its performance can be slower due to additional overhead (e.g., checking for null elements). Additionally, it does not provide direct access to the iteration index.
3. **`some` method**: The `some` method is similar to `forEach`, but it only executes when at least one element matches the condition. This might lead to more iterations in some cases, affecting performance.
4. **`for...of` loop**: The `for...of` loop provides a concise way to iterate over arrays and objects without manual indexing or using indices. However, its performance is not as well-understood as other loops, and it may have additional overhead.

**Libraries and their purpose**

None of the individual test cases rely on any external libraries beyond what's typically included in modern JavaScript environments (e.g., `Array.prototype.forEach()`).

**Special JS features or syntax:**

The only notable feature being tested is the use of `for...of` loop, which allows iterating over arrays without manual indexing. This construct was introduced in ECMAScript 2015 and provides a more concise way to iterate over arrays.

**Other alternatives:**

1. **Loops using traditional indexing**: While not explicitly compared in this benchmark, loops that use traditional indexing (`array[i]`) can also be used with `for` or `forEach`.
2. **Using `map()` and `reduce()` methods**: Instead of using individual loops for each element, you could use `map()` and `reduce()` to achieve similar results.
3. **Using WebAssembly (WASM) performance optimizations**: Modern browsers like Firefox support WASM, which can provide additional performance enhancements for certain workloads.

Keep in mind that the specific choice of loop construct or optimization technique ultimately depends on the particular use case and requirements.

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/115.0

Browser/OS: Firefox 115 on Linux

View result in a separate tab

Test name	Executions per second
for	5277.5 Ops/sec
foreach	5367.4 Ops/sec
some	4924.2 Ops/sec
for..of	692.7 Ops/sec

Related benchmarks:

for vs foreach vs some vs for..of 1 (version: 0)

Compare loop performance

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

Created: one year ago by: Guest

Jump to the latest result

for

foreach

some

for..of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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