Benchmark: for vs foreach vs some vs for..of (short array)

Script Preparation code:

var array = new Array(5);

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

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for	1167943.4 Ops/sec
foreach	10541890.0 Ops/sec
some	10557484.0 Ops/sec
for..of	1785006.6 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Definition**

The benchmark compares the performance of four different loop constructs in JavaScript:

1. **For loop**: An old-school, manual incrementing loop that relies on `array.length` to iterate over the elements.
2. **forEach**: A built-in method that iterates over an array using a callback function.
3. **Some**: Another built-in method that returns a boolean value indicating whether at least one element in the array passes a test (in this case, just checking if any element exists).
4. **For...of loop** (ES6+): A new loop construct that uses a `for` expression to iterate over the elements of an array.

**Script Preparation Code**

The script starts by creating a new JavaScript array with 5 elements:
```javascript
var array = new Array(5);
```
This will be the input for our benchmark.

**Options being compared**

Here's what each loop construct does, along with some pros and cons:

1. **For loop**: Manual incrementing loop that relies on `array.length`. Pros: simple, well-supported by older browsers. Cons: error-prone, slow, and less readable.
2. **ForEach**: Built-in method that iterates over an array using a callback function. Pros: concise, modern, and efficient. Cons: can be slower due to the overhead of a function call, and may not work in older browsers or Node.js versions before 4.x.
3. **Some**: Another built-in method that returns a boolean value indicating whether at least one element passes a test. Pros: simple, fast, and efficient. Cons: doesn't actually iterate over all elements (only stops when the condition is false), which might not be what you want for some use cases.
4. **For...of loop**: A new loop construct that uses a `for` expression to iterate over the elements of an array. Pros: concise, modern, and efficient. Cons: requires ES6+ support (older browsers may not understand this syntax).

**Library usage**

There is no explicit library mentioned in the provided code or benchmark definition.

**Special JS feature or syntax**

The For...of loop uses a special feature called **for...of loops**, which was introduced in ECMAScript 2015 (ES6). This allows you to iterate over an array using a more concise syntax than traditional for loops. This feature is widely supported by modern browsers and Node.js versions.

**Other alternatives**

For non-array elements, you can use other loop constructs like:

* `while` loops
* `do-while` loops
* Recursive functions

Keep in mind that the choice of loop construct ultimately depends on your specific use case, performance requirements, and target audience.

Related benchmarks:

for vs foreach vs some vs for..of (short array) (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 2 months ago):