Benchmark: for(const x of arr) vs. for(let i = 0; i < arr.length; i++)

Tests:

for(const x of arr)
const arr = [] for (let i = 0; i < 10000; i++) { arr.push(i) } for(const hi of arr) { }
for(let i = 0; i < arr.length; ++i)
const arr = [] for (let i = 0; i < 10000; i++) { arr.push(i) } for(let i = 0; i < arr.length; ++i) { const self = arr[i] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for(const x of arr)
for(let i = 0; i < arr.length; ++i)

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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**Benchmark Definition**

The provided JSON represents a benchmark definition for two test cases:

1. `for(const x of arr)`
2. `for(let i = 0; i < arr.length; ++i)`

These are both `for` loops that iterate over an array (`arr`) with a different syntax.

**Options Compared**

In this benchmark, the following options are compared:

* **Syntax**: Two different `for` loop syntaxes are used:
	+ `const x of arr`: This is called the "iterable for" or "array iteration" syntax, introduced in ECMAScript 2015 (ES6). It allows iterating over arrays and other iterable objects using a `for...of` loop.
	+ `let i = 0; i < arr.length; ++i`: This is the traditional `for` loop syntax, where the variable `i` is initialized before the loop and incremented manually inside the loop body.
* **Performance**: The benchmark measures the execution speed of each loop using a timer.

**Pros and Cons**

Here are some pros and cons for each approach:

* **Iterable for (const x of arr)**
	+ Pros:
		- More concise and readable syntax
		- Less boilerplate code required
		- Can be faster due to reduced overhead from manual variable management
	+ Cons:
		- May have slightly worse performance in some cases due to additional overhead from creating an iterator object
* **Traditional for (let i = 0; i < arr.length; ++i)**
	+ Pros:
		- Well-established and widely supported syntax
		- May be faster in some cases due to reduced overhead from iterable creation
	+ Cons:
		- More verbose and less readable syntax
		- Requires manual variable management, which can lead to errors

**Library Used**

In this benchmark, no external libraries are used.

**Special JS Features or Syntax**

The `for...of` loop (const x of arr) is a feature introduced in ECMAScript 2015 (ES6). It allows iterating over arrays and other iterable objects using a single syntax. This feature was added to provide a more concise and readable way to iterate over collections.

**Other Alternatives**

If you're interested in exploring alternative loop constructs, here are some examples:

* `for...in` loop: Iterates over the properties of an object.
* `forEach` method: A part of the DOM API, allows iterating over elements in a document or subdocument.
* Array.prototype.map(): Applies a transformation function to each element in an array and returns a new array.

Keep in mind that these alternatives may have different use cases and performance characteristics compared to traditional `for` loops.

Related benchmarks:

for(const x of arr) vs. for(let i = 0; i < arr.length; i++) (version: 0)

Comparing performance of: for(const x of arr) vs for(let i = 0; i < arr.length; ++i)

Created: 4 years ago by: Guest

Jump to the latest result

for(const x of arr)

for(let i = 0; i < arr.length; ++i)

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):