Benchmark: Array for vs. some

Script Preparation code:

var arr = new Array(10000).fill(null);

Tests:

for
for (let i = 0; i < arr.length; i++) { if (i === 500) { return true; } }
optimized for
for (let i = 0, l = arr.length; i < l; i++) { if (i === 500) { return true; } }
includes
return arr.some((v, i) => i === 500);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
optimized for
includes

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and its pros/cons.

**Benchmark Overview**

The benchmark is designed to compare three different approaches for checking if a specific element exists in an array:

1. **Traditional For Loop**: Iterates over the array using a traditional `for` loop.
2. **Optimized For Loop**: Uses a shorter syntax by declaring variables before they are used (`let i = 0, l = arr.length;`) and checks for the condition within the loop body.
3. **Array.prototype.some()**: Utilizes the `some()` method of the array prototype, which returns `true` if at least one element in the array passes the provided callback function.

**Comparison**

The benchmark tests each approach on a fixed array of length 10,000 with a specific condition that should return `false`. The results are compared across different browsers and devices.

**Pros and Cons:**

1. **Traditional For Loop**:
	* Pros: Easy to understand, well-supported by most browsers.
	* Cons: Inefficient (iterates over the entire array) and slow for large arrays.
2. **Optimized For Loop**:
	* Pros: Slightly more efficient than traditional `for` loop and easier to read due to variable declarations before use.
	* Cons: Still iterates over the entire array, although with fewer iterations than traditional `for`.
3. **Array.prototype.some()**:
	* Pros: Fastest approach (as it can stop iterating as soon as it finds a match) and concise.
	* Cons: Not supported by all browsers (older versions of Chrome, for example).

**Special JavaScript Features/Syntax**

The benchmark uses the `let` keyword with variable declarations before use in the optimized loop. This is a more modern JavaScript feature introduced in ECMAScript 2015.

**Library/Functionality Used**

None in this specific benchmark.

**Device and Browser Considerations**

The results are reported for different browsers (Chrome Mobile) on various devices (Android). The performance may vary depending on the device's hardware and software configuration.

**Other Alternatives**

If you need to check if an element exists in an array, other approaches might be considered:

* Using `Array.prototype.includes()` method: This is another convenient option that returns `true` if the element is present. It's supported by most modern browsers.
* Using a custom function or library for performance-critical applications.

Keep in mind that these alternatives may have their own set of pros and cons, depending on your specific requirements and use case.

Related benchmarks:

Array for vs. some (version: 0)

Comparing performance of: for vs optimized for vs includes

Created: 7 years ago by: Registered User

Jump to the latest result

for

optimized for

includes

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):