Benchmark: array iteration speed

Script Preparation code:

var array = new Array(100);

Tests:

for
for (let 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]; }
for (declaration outside)
let i = 0; let l = array.length; for (i; i < l; i++) { array[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
for..of
for (declaration outside)

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

Browser/OS: Chrome 110 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for	143423.9 Ops/sec
foreach	3883806.8 Ops/sec
some	3967811.8 Ops/sec
for..of	243803.5 Ops/sec
for (declaration outside)	285825.8 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**What is being tested?**

The benchmark is designed to compare the performance of different loop constructs in JavaScript, specifically:

* `for` loops
* `forEach` methods (array iteration)
* `some` methods (array iteration)
* `for...of` loops

These loops are used to iterate over an array and perform some operation on each element.

**Options compared**

The benchmark compares the performance of the following options:

1. **Traditional `for` loop**: A classic loop construct that uses a counter variable (`i`) to control the iteration.
2. **Array `forEach` method**: A built-in method that iterates over an array, executing a provided callback function on each element.
3. **Array `some` method**: Another built-in method that tests whether at least one element in an array satisfies a given condition.
4. **`for...of` loop**: A newer loop construct introduced in ECMAScript 2015 (ES6), which iterates over arrays using a special syntax.

**Pros and cons of each approach**

1. **Traditional `for` loop**:
	* Pros: Simple, lightweight, and widely supported.
	* Cons: Can be error-prone if not used correctly, as the counter variable can lead to off-by-one errors.
2. **Array `forEach` method**:
	* Pros: Concise, readable, and easy to understand.
	* Cons: Can be slower than traditional loops, especially for large arrays, since it creates a new scope and executes the callback function for each element.
3. **Array `some` method**:
	* Pros: Efficient for testing conditions on individual elements.
	* Cons: Not designed for iterating over entire arrays; instead, it returns a boolean indicating whether any element satisfies the condition.
4. **`for...of` loop**:
	* Pros: Modern, concise, and easy to read.
	* Cons: Less widely supported in older browsers (pre-ES6) or environments.

**Library usage**

The `forEach` method is used by MeasureThat.net, as it provides a convenient way to iterate over arrays without worrying about the underlying implementation details.

**Special JS features**

None of the benchmarked constructs rely on special JavaScript features, such as async/await, promises, or generator functions. They all focus on the basic loop constructs and their performance characteristics.

**Other alternatives**

If you need to compare different iteration methods in your own JavaScript code, consider exploring other approaches, such as:

* Using `map` method instead of loops for array transformations
* Employing iterators (e.g., with generators) for more complex iterations or recursive processing
* Leveraging the `requestAnimationFrame` API for high-performance animation and rendering tasks

Related benchmarks:

array iteration speed (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs some vs for..of vs for (declaration outside)

Created: 2 years ago by: Guest

Jump to the latest result

for

foreach

some

for..of

for (declaration outside)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):