Benchmark: for..of VS forEach

Script Preparation code:

var values = new Array(10000);
for (var i = 0; i < values.length; i++) values[i]=i;

Tests:

forEach
var sum = 0; function add(v) { sum += v} values.forEach(add);
for..of
var sum = 0; for (var v of values) sum += v;
forEach func
var sum = 0; values.forEach(function(v) { sum += v } );
for of transpiled
var sum = 0; for (var _i = 0, values_1 = values; _i < values_1.length; _i++) { var v = values_1[_i]; sum += v; }
for of transpiled simple
var sum = 0; for (var i = 0; i < values.length; i++) sum += values[i];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
forEach
for..of
forEach func
for of transpiled
for of transpiled simple

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days 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 test that compares the performance of three different approaches to iterate over an array in modern JavaScript:

1. **for..of**: A built-in iteration syntax introduced in ECMAScript 2015.
2. **forEach**: A method on Array objects, also part of ECMAScript 2015.
3. Two variants of `for` loops:
	* **For loop with function callback**: A classic `for` loop with a separate function passed as an argument to iterate over the array elements.
	* **Transpiled for loop**: A `for` loop that uses the transpiled version of the `for...of` syntax, which is compatible with older JavaScript engines.

**Options compared:**

The benchmark compares the performance of each approach:

1. **For..of**
2. **forEach func** (a function callback variant of `forEach`)
3. **For loop with function callback**
4. **Transpiled for loop** (a transpiled version of a classic `for` loop)

**Pros and Cons:**

Here's a brief summary of the pros and cons of each approach:

1. **For..of**:
	* Pros: Native support, concise syntax, easy to read.
	* Cons: May not be supported in older browsers or engines.
2. **forEach func** (function callback variant):
	* Pros: Works with any array-like object, can be used with other data structures.
	* Cons: Requires an additional function definition, less efficient due to the overhead of function creation.
3. **For loop with function callback**:
	* Pros: Wide browser support, easy to implement.
	* Cons: Less concise syntax, more prone to errors due to variable scoping.
4. **Transpiled for loop** (transpiled version of classic `for` loop):
	* Pros: Compatibility with older browsers and engines, similar performance to native `for..of`.
	* Cons: Additional compilation step required.

**Library usage:**

None of the benchmark tests use any external libraries.

**Special JS feature or syntax:**

The tests utilize ECMAScript 2015 features, specifically:

1. **Arrow functions**: Used in the `forEach func` test.
2. **Transpilation**: The transpiled version of the classic `for` loop uses a modified version of the syntax to make it compatible with older engines.

**Other alternatives:**

If you're looking for alternative approaches to iterate over an array, consider:

1. **While loops**: A traditional loop construct that can be used with arrays.
2. **Lodash**: A popular utility library that provides various iteration functions, including `forEach`.

Keep in mind that the choice of iteration approach depends on your specific use case, performance requirements, and target browser support.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0

Browser/OS: Firefox 60 on Windows

View result in a separate tab

Test name	Executions per second
forEach	57335.4 Ops/sec
for..of	16389.5 Ops/sec
forEach func	57372.9 Ops/sec
for of transpiled	86221.8 Ops/sec
for of transpiled simple	12018.3 Ops/sec

Related benchmarks:

for..of VS forEach (version: 0)

Comparing performance of: forEach vs for..of vs forEach func vs for of transpiled vs for of transpiled simple

Created: 7 years ago by: Guest

Jump to the latest result

forEach

for..of

forEach func

for of transpiled

for of transpiled simple

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):