Benchmark: for x of y vs loop vs for each

Script Preparation code:

var players = new Array(50).fill({x: 'a'});

Tests:

loop
let playerLen = players.length; for (let i = 0; i < playerLen; ++i) { let player = players[i]; if (player) { player.x = "a"; }; };
for x of y
for (let player of players) { if (player) { player.x = "a"; }; };
forEach
players.forEach(player => { if (player) { player.y = "a"; }; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
loop
for x of y
forEach

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the world of MeasureThat.net and explore what's being tested in this benchmark.

**Benchmark Overview**

The benchmark compares three approaches to iterate over an array: `for` loop, `for...of` loop (also known as "iteration" or " foreach"), and `forEach()` method. The goal is to determine which approach is the most efficient for a given test case.

**Test Case 1: Loop**

In this test case, we have a simple `for` loop that iterates over an array of objects using traditional indexing (`players[i]`). The loop increments a counter variable (`i`) from 0 to `playerLen - 1`.

Here's what's being tested:

* A `for` loop with traditional indexing.
* Performance: How fast can the browser execute this loop?

**Test Case 2: For x of y**

This test case uses the `for...of` loop, also known as "iteration" or "forEach". This syntax allows you to iterate over an array without explicitly indexing into it.

Here's what's being tested:

* A `for...of` loop that iterates over an array using the `of` keyword.
* Performance: How fast can the browser execute this loop?

**Test Case 3: ForEach**

In this test case, we have a call to the `forEach()` method, which also allows you to iterate over an array without explicit indexing.

Here's what's being tested:

* A `forEach()` method that iterates over an array.
* Performance: How fast can the browser execute this loop?

**Library Used**

In all three test cases, we're using a JavaScript library (or rather, a feature of JavaScript) to create and manipulate arrays. Specifically:

* The `Array.prototype.forEach()` method is used in Test Case 3.
* There's no explicit library or framework mentioned in the benchmark definition or individual test cases.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **For Loop**
	* Pros:
		+ Familiar syntax
		+ No overhead of additional function calls
	* Cons:
		+ Requires manual indexing, which can be error-prone
2. **For x of y**
	* Pros:
		+ Elegant syntax
		+ Less prone to errors compared to traditional `for` loops
	* Cons:
		+ May incur a small overhead due to the additional function call
3. **ForEach**
	* Pros:
		+ Convenient and expressive syntax
		+ Built-in support for iteration
	* Cons:
		+ May have a higher overhead compared to traditional `for` loops

**Other Alternatives**

There are other ways to iterate over arrays in JavaScript, such as:

1. **While Loop**: A traditional `while` loop can also be used to iterate over an array.
2. **Array.prototype.map()`, `Array.prototype.filter()`, and `Array.prototype.reduce()` methods: These methods provide a functional programming style of iteration, which can be more concise but may have different performance characteristics.

Keep in mind that these alternative approaches might not be directly comparable to the `for` loop, `for...of` loop, or `forEach()` method, as they often involve additional function calls or transformations on the data.

I hope this explanation helps you understand what's being tested in this benchmark!

Related benchmarks:

for x of y vs loop vs for each (version: 0)

Comparing performance of: loop vs for x of y vs forEach

Created: 4 years ago by: Guest

Jump to the latest result

loop

for x of y

forEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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