Benchmark: Array.join vs String join

Script Preparation code:

var arr = Array.from(1000).fill("test");

Tests:

arr join
arr.join(",");
string join
let str = ""; for(let i = 0; i<arr.length; i++){ str +=arr[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arr join
string join

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36 OPR/102.0.0.0

Browser/OS: Opera 102 on Windows

View result in a separate tab

Test name	Executions per second
arr join	26317972.0 Ops/sec
string join	27927836.0 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark measures the performance difference between two approaches: using `Array.join()` and concatenating strings manually (`for` loop) to concatenate an array of strings.

**What is being tested?**

Two test cases are compared:

1. **`arr.join(',')`:** This method takes an array as input and returns a string by joining all the elements in the array with a specified separator (in this case, a comma).
2. **Manual concatenation (`for` loop):** This approach manually iterates over the array, appending each element to a string using the `+=` operator.

**Options compared**

The benchmark compares the performance of two approaches:

* **`Array.join()`**: A built-in JavaScript method that joins an array into a string.
* **Manual concatenation (`for` loop)**: A custom implementation that uses a `for` loop to iterate over the array and concatenate the elements to a string.

**Pros and Cons**

### `Array.join()`

Pros:

* Concise and efficient way to join arrays into strings.
* Built-in JavaScript method, so it's familiar and widely supported.

Cons:

* Can be slower than manual concatenation for very large datasets due to the overhead of creating a new string and handling edge cases.
* Requires a separator as an argument, which may not always be desirable.

### Manual concatenation (`for` loop)

Pros:

* Can be faster than `Array.join()` for very large datasets since it avoids the overhead of creating a new string and handles edge cases in-place.
* Allows customization of the separator or other parameters.

Cons:

* More verbose and less concise than using `Array.join()`.
* Requires manual handling of edge cases, such as null or undefined values in the array.

**Other considerations**

When choosing between these two approaches, consider the following factors:

* **Performance**: For small to medium-sized datasets, `Array.join()` might be sufficient. However, for very large datasets (e.g., tens of thousands of elements), manual concatenation using a `for` loop may be faster.
* **Readability and maintainability**: If readability is more important than performance, `Array.join()` is likely a better choice since it's more concise and expressive.

**Library or special JS feature**

None are mentioned in the provided benchmark definition. The focus is on comparing two simple approaches to concatenate an array of strings.

If you have any further questions or would like to explore other aspects of this benchmark, feel free to ask!

Related benchmarks:

Array.join vs String join (version: 0)

Comparing performance of: arr join vs string join

Created: one year ago by: Guest

Jump to the latest result

arr join

string join

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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