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

Script Preparation code:

var array = new Array(1000);

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]; }
for in
for (var i in array) { array[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
for..of
for in

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36 Edg/141.0.0.0

Browser/OS: Chrome 141 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for	632981.6 Ops/sec
foreach	1161228.9 Ops/sec
some	1178608.0 Ops/sec
for..of	160228.0 Ops/sec
for in	718678.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is being tested?**

The provided JSON represents a benchmark that compares the performance of six different loop iteration methods in JavaScript:

1. Traditional `for` loop
2. `forEach` method
3. `some` method
4. `for...of` loop (introduced in ECMAScript 2015)
5. `for...in` loop (also known as property iteration)

These loops are used to iterate over an array, performing some operation on each element.

**Options compared**

The benchmark compares the performance of these six loop methods under different conditions:

* Each method is executed a fixed number of times (1000 iterations)
* The loops are executed in their respective order

The benchmark aims to answer which loop iteration method performs best and why.

**Pros and Cons of each approach:**

1. **Traditional `for` loop**:
	* Pros: Wide support, easy to understand and maintain
	* Cons: Can be slower due to the overhead of incrementing the index variable
2. **`forEach` method**:
	* Pros: Convenient and concise, often preferred in modern JavaScript code
	* Cons: May not be as efficient as traditional loops, especially for large arrays
3. **`some` method**:
	* Pros: Can exit early if a condition is met, potentially improving performance
	* Cons: Less intuitive than other methods, may lead to unexpected behavior
4. **`for...of` loop**:
	* Pros: Modern and concise, eliminates the need for index variables
	* Cons: May not be as efficient as traditional loops due to array indexing overhead
5. **`for...in` loop**:
	* Pros: Similar to traditional `for` loop, but uses property iteration
	* Cons: Can lead to issues with array objects and prototype chains

**Library usage**

None of the test cases use any external libraries.

**Special JS features or syntax**

The benchmark does not explicitly mention any special JavaScript features or syntax. However, it's worth noting that the `for...of` loop relies on ECMAScript 2015 (ES6) support.

**Other alternatives**

If you're interested in exploring alternative loop iteration methods, consider the following:

* **Array.prototype.every()` and `Array.prototype.some()`: These methods are similar to `forEach`, but with a different signature and behavior.
* **`Map.forEach()` and `Set.forEach()`**: If you need to iterate over Maps or Sets, these methods provide an efficient way to do so.

In conclusion, the benchmark provides a comprehensive comparison of six loop iteration methods in JavaScript. By understanding the pros and cons of each approach, developers can make informed decisions about which method to use for specific tasks, ultimately optimizing performance and code readability.

Related benchmarks:

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

Compare loop performance

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

Created: one year ago by: Guest

Jump to the latest result

for

foreach

some

for..of

for in

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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